Initial port of PostgreSQL egg to CHICKEN 54.0.0

1 files changed, 1360 insertions, 0 deletions

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+++ b/postgresql.scm
@@ -0,0 +1,1360 @@
+;;; Bindings to the PostgreSQL C library
+;;
+;; Copyright (C) 2008-2014 Peter Bex
+;; Copyright (C) 2004 Johannes Grødem <johs@copyleft.no>
+;; Redistribution and use in source and binary forms, with or without
+;; modification, is permitted.
+;;
+;; THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
+;; OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+;; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+;; ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
+;; LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+;; CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+;; OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+;; BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+;; LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+;; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+;; USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+;; DAMAGE.
+
+(module postgresql
+ (type-parsers update-type-parsers! default-type-parsers
+  char-parser bool-parser bytea-parser numeric-parser
+  make-array-parser make-composite-parser
+  scheme-value->db-value type-unparsers update-type-unparsers!
+  default-type-unparsers bool-unparser vector-unparser list-unparser
+  
+  connect reset-connection disconnect connection? connected?
+  
+  query query* with-transaction in-transaction?
+  
+  result? clear-result! row-count column-count
+  column-index column-name column-names column-format
+  column-type column-type-modifier table-oid table-column-index
+  value-at row-values row-alist column-values affected-rows inserted-oid
+
+  invalid-oid
+  
+  escape-string escape-bytea unescape-bytea quote-identifier
+
+  put-copy-data put-copy-end get-copy-data
+  
+  row-fold row-fold* row-fold-right row-fold-right*
+  row-for-each row-for-each* row-map row-map*
+  column-fold column-fold* column-fold-right column-fold-right*
+  column-for-each column-for-each* column-map column-map*
+  copy-query-fold copy-query*-fold copy-query-fold-right copy-query*-fold-right
+  copy-query-for-each copy-query*-for-each copy-query-map copy-query*-map
+  call-with-output-copy-query call-with-output-copy-query*
+  with-output-to-copy-query with-output-to-copy-query*)
+
+ (import scheme
+         (chicken base)
+         (chicken foreign)
+         (chicken string)
+         (chicken port)
+         (chicken memory)
+         (chicken condition)
+         (chicken format)
+         (chicken gc)
+         (chicken blob)
+         srfi-1
+         srfi-4
+         srfi-13
+         srfi-18
+         srfi-69
+         sql-null)
+
+(import-for-syntax (chicken string))
+
+(foreign-declare "#include <libpq-fe.h>")
+
+(define-foreign-type pg-polling-status (enum "PostgresPollingStatusType"))
+(define-foreign-variable PGRES_POLLING_FAILED pg-polling-status)
+(define-foreign-variable PGRES_POLLING_READING pg-polling-status)
+(define-foreign-variable PGRES_POLLING_WRITING pg-polling-status)
+(define-foreign-variable PGRES_POLLING_OK pg-polling-status)
+
+(define-foreign-type pg-exec-status (enum "ExecStatusType"))
+(define-foreign-variable PGRES_EMPTY_QUERY pg-exec-status)
+(define-foreign-variable PGRES_COMMAND_OK pg-exec-status)
+(define-foreign-variable PGRES_TUPLES_OK pg-exec-status)
+(define-foreign-variable PGRES_COPY_OUT pg-exec-status)
+(define-foreign-variable PGRES_COPY_IN pg-exec-status)
+(define-foreign-variable PGRES_BAD_RESPONSE pg-exec-status)
+(define-foreign-variable PGRES_NONFATAL_ERROR pg-exec-status)
+(define-foreign-variable PGRES_FATAL_ERROR pg-exec-status)
+
+(define-foreign-type pgconn* (c-pointer "PGconn"))
+
+(define PQconnectStart (foreign-lambda pgconn* PQconnectStart (const c-string)))
+(define PQconnectPoll (foreign-lambda pg-polling-status PQconnectPoll pgconn*))
+(define PQresetStart (foreign-lambda bool PQresetStart pgconn*))
+(define PQresetPoll (foreign-lambda pg-polling-status PQresetPoll pgconn*))
+(define PQfinish (foreign-lambda void PQfinish pgconn*))
+(define PQstatus (foreign-lambda (enum "ConnStatusType") PQstatus (const pgconn*)))
+(define PQerrorMessage (foreign-lambda c-string PQerrorMessage (const pgconn*)))
+
+;(define-foreign-type oid "Oid")
+(define-foreign-type oid unsigned-int)
+
+(define invalid-oid (foreign-value "InvalidOid" oid))
+
+(define PQisBusy (foreign-lambda bool PQisBusy pgconn*))
+(define PQconsumeInput (foreign-lambda bool PQconsumeInput pgconn*))
+
+(define-foreign-type pgresult* (c-pointer "PGresult"))
+
+(define PQgetResult (foreign-lambda pgresult* PQgetResult pgconn*))
+(define PQresultStatus (foreign-lambda pg-exec-status PQresultStatus (const pgresult*)))
+(define PQresultErrorMessage (foreign-lambda c-string PQresultErrorMessage (const pgresult*)))
+(define PQresultErrorField (foreign-lambda c-string PQresultErrorField (const pgresult*) int))
+
+(define PQclear (foreign-lambda void PQclear pgresult*))
+(define PQnfields (foreign-lambda int PQnfields (const pgresult*)))
+(define PQntuples (foreign-lambda int PQntuples (const pgresult*)))
+(define PQfname (foreign-lambda c-string PQfname (const pgresult*) int))
+(define PQfnumber (foreign-lambda int PQfnumber (const pgresult*) (const c-string)))
+(define PQftable (foreign-lambda oid PQftable (const pgresult*) int))
+(define PQftablecol (foreign-lambda int PQftablecol (const pgresult*) int))
+(define PQfformat (foreign-lambda int PQfformat (const pgresult*) int))
+(define PQftype (foreign-lambda oid PQftype (const pgresult*) int))
+(define PQfmod (foreign-lambda int PQfmod (const pgresult*) int))
+(define PQgetisnull (foreign-lambda bool PQgetisnull (const pgresult*) int int))
+(define PQgetlength (foreign-lambda int PQgetlength (const pgresult*) int int))
+(define PQgetvalue-ptr (foreign-lambda (c-pointer char) PQgetvalue (const pgresult*) int int))
+(define PQcmdTuples (foreign-lambda nonnull-c-string PQcmdTuples pgresult*))
+(define PQoidValue (foreign-lambda oid PQoidValue pgresult*))
+
+(define PQputCopyData (foreign-lambda int PQputCopyData pgconn* scheme-pointer int))
+(define PQputCopyEnd (foreign-lambda int PQputCopyEnd pgconn* (const c-string)))
+(define PQgetCopyData (foreign-lambda int PQgetCopyData pgconn* (c-pointer (c-pointer char)) bool))
+
+(define memcpy (foreign-lambda c-pointer "C_memcpy" scheme-pointer c-pointer size_t))
+
+(define (srfi-4-vector? x) ; Copied from ##sys#srfi-4-vector? from 4.8.3
+  (and (##core#inline "C_blockp" x)
+       (##sys#generic-structure? x)
+       (memq (##sys#slot x 0)
+             '(u8vector u16vector s8vector s16vector u32vector s32vector f32vector f64vector))))
+
+;; TODO: Create a real callback system?
+(foreign-declare "static void nullNoticeReceiver(void *arg, const PGresult *res){ }")
+
+(define-syntax define-foreign-int
+  (er-macro-transformer
+   (lambda (e r c)
+     ;; cannot rename define-foreign-variable; it's a really special form
+     `(define-foreign-variable ,(cadr e) int ,(conc "(int) " (cadr e))))))
+
+(define-syntax define-pgdiag-constants
+  (syntax-rules ()
+    ((_ (?condition ?constant0 ...) ?more ...)
+     (begin (cond-expand
+              (?condition (define-foreign-int ?constant0) ...)
+              (else (define ?constant0 #f) ...))
+            (define-pgdiag-constants ?more ...)))
+    ((_ ?constant0 ?more ...)
+     (begin (define-foreign-int ?constant0)
+            (define-pgdiag-constants ?more ...)))
+    ((_) (void))))
+
+(define-pgdiag-constants
+  PG_DIAG_SEVERITY PG_DIAG_SQLSTATE PG_DIAG_CONTEXT PG_DIAG_MESSAGE_PRIMARY
+  PG_DIAG_MESSAGE_DETAIL PG_DIAG_MESSAGE_HINT PG_DIAG_STATEMENT_POSITION
+  PG_DIAG_SOURCE_FILE PG_DIAG_SOURCE_LINE PG_DIAG_SOURCE_FUNCTION
+  
+  (has-diag-query-position
+   PG_DIAG_INTERNAL_QUERY PG_DIAG_INTERNAL_POSITION)
+  
+  (has-diag-schema-info
+   PG_DIAG_SCHEMA_NAME PG_DIAG_TABLE_NAME PG_DIAG_COLUMN_NAME
+   PG_DIAG_DATATYPE_NAME PG_DIAG_CONSTRAINT_NAME))
+
+;; Helper procedure for lists (TODO: use ANY instead of IN with an array?)
+(define (in-list len)
+  (string-intersperse
+   (list-tabulate len (lambda (p) (conc "$" (add1 p)))) ","))
+
+(define (postgresql-error subtype loc message . args)
+  (signal (apply make-pg-condition subtype loc message args)))
+
+(define (make-pg-condition subtype loc message . args)
+  (make-composite-condition
+   (make-property-condition
+    'exn 'location loc 'message message 'arguments args)
+   (make-property-condition 'postgresql)
+   (if (condition? subtype) subtype (make-property-condition subtype))))
+
+;;;;;;;;;;;;;;;;;;;;;;;;
+;;;; Type parsers
+;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (char-parser str) (string-ref str 0))
+
+(define (bool-parser str) (string=? str "t"))
+
+(define (numeric-parser str)
+  (or (string->number str)
+      (postgresql-error 'parse 'numeric-parser "Unable to parse number" str)))
+
+(define (bytea-parser str)
+  (unescape-bytea str))
+
+;; Here be dragons
+(define (make-array-parser element-parser #!optional (delim #\,))
+  (define (parse str)
+    (if (string-ci=? "NULL" str)
+        (sql-null)
+        (element-parser str)))
+  (lambda (str)
+    (let loop ((chars (let ignore-bounds ((chars (string->list str)))
+                        (if (char=? (car chars) #\{)
+                            chars
+                            (ignore-bounds (cdr chars)))))
+               (result (list)))
+      (if (null? chars)
+          (car result)                ; Should contain only one vector
+          (case (car chars)
+            ((#\{) (receive (value rest-chars)
+                       (loop (cdr chars) (list))
+                     (loop rest-chars (cons value result))))
+            ((#\}) (values (list->vector (reverse! result)) (cdr chars)))
+            ((#\") (let consume-string ((chars (cdr chars))
+                                        (consumed (list)))
+                     (case (car chars)
+                       ((#\\) (consume-string ; Don't interpret, just add it
+                               (cddr chars) (cons (cadr chars) consumed)))
+                       ((#\") (loop (cdr chars)
+                                    (cons (element-parser
+                                           (reverse-list->string consumed))
+                                          result)))
+                       (else (consume-string (cdr chars)
+                                             (cons (car chars) consumed))))))
+            ((#\tab #\newline #\space) (loop (cdr chars) result))
+            (else
+             (if (char=? (car chars) delim)
+                 (loop (cdr chars) result)
+                 (let consume-string ((chars chars)
+                                      (consumed (list)))
+                   (cond
+                    ((char=? (car chars) delim)
+                     (loop (cdr chars)
+                           (cons (parse (reverse-list->string consumed))
+                                 result)))
+                    ((or (char=? (car chars) #\})
+                         (char=? (car chars) #\}))
+                     (loop chars
+                           (cons (parse (reverse-list->string consumed))
+                                 result)))
+                    (else (consume-string (cdr chars)
+                                          (cons (car chars) consumed))))))))))))
+
+(define (make-composite-parser element-parsers)
+  (define (parse str element-parser)
+    (if (string=? "" str)
+        (sql-null)
+        (element-parser str)))
+  (lambda (str)
+    (let loop ((chars (cdr (string->list (string-trim str)))) ; skip leading (
+               (maybe-null? #t)
+               (result (list))
+               (parsers element-parsers))
+      (case (car chars)
+        ((#\)) (reverse! (if maybe-null?
+                             (cons (sql-null) result)
+                             result)))
+        ((#\") (let consume-string ((chars (cdr chars))
+                                    (consumed (list)))
+                 (case (car chars)
+                   ((#\\) (consume-string ; Don't interpret, just add it
+                           (cddr chars) (cons (cadr chars) consumed)))
+                   ((#\") (if (char=? #\" (cadr chars)) ; double escapes
+                              (consume-string (cddr chars)
+                                              (cons #\" consumed))
+                              (let skip-spaces ((chars (cdr chars)))
+                                (case (car chars)
+                                  ((#\space #\newline #\tab)
+                                   (skip-spaces (cdr chars)))
+                                  ((#\,)
+                                   (loop (cdr chars)
+                                         #t
+                                         (cons ((car parsers)
+                                                (reverse-list->string consumed))
+                                               result)
+                                         (cdr parsers)))
+                                  ((#\)) (loop chars
+                                               #f
+                                               (cons ((car parsers)
+                                                      (reverse-list->string consumed))
+                                                     result)
+                                               (cdr parsers)))
+                                  (else
+                                   (postgresql-error
+                                    'parse 'make-composite-parser
+                                    "Bogus trailing characters" str))))))
+                   (else (consume-string (cdr chars)
+                                         (cons (car chars) consumed))))))
+        (else (let consume-string ((chars chars)
+                                   (consumed (list)))
+                (case (car chars)
+                  ((#\,) (loop (cdr chars)
+                               #t
+                               (cons (parse (reverse-list->string consumed)
+                                            (car parsers))
+                                     result)
+                               (cdr parsers)))
+                  ;; Nothing should precede this one
+                  ((#\)) (loop chars
+                               #f
+                               (cons (parse (reverse-list->string consumed)
+                                            (car parsers))
+                                     result)
+                               (cdr parsers)))
+                  (else (consume-string (cdr chars)
+                                        (cons (car chars) consumed))))))))))
+
+;; Array parsers and composite parsers are automatically cached when such
+;; a value is requested.
+(define default-type-parsers
+  (make-parameter
+   `(("text" . ,identity)
+     ("bytea" . ,bytea-parser)
+     ("char" . ,char-parser)
+     ("bpchar" . ,identity)
+     ("bool" . ,bool-parser)
+     ("int8" . ,numeric-parser)
+     ("int4" . ,numeric-parser)
+     ("int2" . ,numeric-parser)
+     ("float4" . ,numeric-parser)
+     ("float8" . ,numeric-parser)
+     ("numeric" . ,numeric-parser)
+     ("oid" . ,numeric-parser)
+     ;; Nasty hack, or clever hack? :)
+     ("record" . ,(make-composite-parser (circular-list identity))))))
+
+;;;;;;;;;;;;;;;;;;;;;;;
+;;;; Type unparsers
+;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (scheme-value->db-value conn value)
+  (cond ((find (lambda (parse?)
+                 ((car parse?) value))
+               (pg-connection-type-unparsers conn)) =>
+               (lambda (parse)
+                 ((cdr parse) conn value)))
+        (else value)))
+
+(define (bool-unparser conn b)
+  (if b "TRUE" "FALSE"))
+
+(define (vector-unparser conn v)
+  (let loop ((result (list))
+             (pos 0)
+             (len (vector-length v)))
+    (if (= pos len)
+        (string-append "{" (string-intersperse (reverse! result) ",") "}")
+        (let* ((value (vector-ref v pos))
+               (unparsed-value (scheme-value->db-value conn value))
+               (serialized (cond
+                            ((sql-null? unparsed-value) "NULL")
+                            ((not (string? unparsed-value))
+                             (postgresql-error
+                              'unparse 'vector-unparser
+                              "Param value is not string" unparsed-value))
+                            ((vector? value) unparsed-value) ;; don't quote!
+                            (else
+                             (sprintf "\"~A\""
+                               (string-translate*
+                                unparsed-value
+                                '(("\\" . "\\\\") ("\"" . "\\\""))))))))
+          (loop (cons serialized result) (add1 pos) len)))))
+
+(define (list-unparser conn l)
+  (let loop ((result (list))
+             (items l))
+    (if (null? items)
+        (string-append "(" (string-intersperse (reverse! result) ",") ")")
+        (let* ((unparsed-value (scheme-value->db-value conn (car items)))
+               (serialized (cond
+                            ((sql-null? unparsed-value) "")
+                            ((not (string? unparsed-value))
+                             (postgresql-error
+                              'unparse 'list-unparser
+                              "Param value is not string" unparsed-value))
+                            (else
+                             (sprintf "\"~A\""
+                               (string-translate*
+                                unparsed-value
+                                '(("\\" . "\\\\") ("\"" . "\\\""))))))))
+          (loop (cons serialized result) (cdr items))))))
+
+(define default-type-unparsers
+  (make-parameter
+   `((,string? . ,(lambda (conn s) s))
+     (,u8vector? . ,(lambda (conn v) (u8vector->blob/shared v)))
+     (,char? . ,(lambda (conn c) (string c)))
+     (,boolean? . ,bool-unparser)
+     (,number? . ,(lambda (conn n) (number->string n)))
+     (,vector? . ,vector-unparser)
+     (,pair? . ,list-unparser))))
+
+;; Retrieve type-oids from PostgreSQL:
+(define (update-type-parsers! conn #!optional new-type-parsers)
+  (let ((type-parsers (or new-type-parsers (pg-connection-type-parsers conn)))
+        (ht (make-hash-table))
+        (result '()))
+    (pg-connection-oid-parsers-set! conn ht)
+    (pg-connection-type-parsers-set! conn type-parsers)
+    (unless (null? type-parsers)   ; empty IN () clause is not allowed
+      (row-for-each*
+       (lambda (oid typname)
+         (and-let* ((procedure (assoc typname type-parsers)))
+           (hash-table-set! ht (string->number oid) (cdr procedure))))
+       (query* conn
+               (sprintf
+                   "SELECT oid, typname FROM pg_type WHERE typname IN (~A)"
+                 (in-list (length type-parsers)))
+               (map car type-parsers) raw: #t)))))
+
+(define (update-type-unparsers! conn new-type-unparsers)
+  (pg-connection-type-unparsers-set! conn new-type-unparsers))
+
+;;;;;;;;;;;;;;;;;;;;
+;;;; Connections
+;;;;;;;;;;;;;;;;;;;;
+
+(define-record pg-connection
+  ptr type-parsers oid-parsers type-unparsers transaction-depth)
+(define connection? pg-connection?)
+(define type-parsers pg-connection-type-parsers)
+(define type-unparsers pg-connection-type-unparsers)
+
+(define (connected? conn) (not (not (pg-connection-ptr conn))))
+
+(define (pgsql-connection->fd conn)
+  ((foreign-lambda int PQsocket pgconn*) (pg-connection-ptr conn)))
+
+(define (wait-for-connection! conn poll-function)
+  (let ((conn-fd (pgsql-connection->fd conn))
+        (conn-ptr (pg-connection-ptr conn)))
+    (let loop ((result (poll-function conn-ptr)))
+      (cond ((= result PGRES_POLLING_OK) (void))
+            ((= result PGRES_POLLING_FAILED)
+             (let ((message (PQerrorMessage conn-ptr)))
+               (disconnect conn)
+               (postgresql-error
+                'connect 'connect
+                (conc "Polling Postgres database failed: " message) conn)))
+            ((member result (list PGRES_POLLING_WRITING PGRES_POLLING_READING))
+             (thread-wait-for-i/o! conn-fd (if (= PGRES_POLLING_READING result)
+                                               #:input
+                                               #:output))
+             (loop (poll-function conn-ptr)))
+            (else
+             (postgresql-error
+              'internal 'connect
+              (conc "Internal error! Unknown status code: " result) conn))))))
+
+(cond-expand
+  ((not has-connectdb-params)
+   (define (alist->connection-spec alist)
+     (string-join
+      (map (lambda (subspec)
+             (sprintf "~A='~A'"
+               (car subspec) ;; this had better not contain [ =\']
+               (string-translate* (->string (cdr subspec))
+                                  '(("\\" . "\\\\") ("'" . "\\'")))))
+           alist))))
+  (else))
+
+(define (connect-start spec)
+  (if (string? spec)
+      (PQconnectStart spec)
+      (cond-expand
+        (has-connectdb-params
+         (let ((len (length spec)))
+           ((foreign-lambda* pgconn* ((scheme-object cons) (scheme-pointer keybuf)
+                                      (scheme-pointer valbuf) (int len))
+              "const char **key = (const char **)keybuf;"
+              "const char **val = (const char **)valbuf;"
+              "int i;"
+              "for (i=0; i < len; ++i,cons=C_u_i_cdr(cons)) {"
+              "    C_word kvpair = C_u_i_car(cons);"
+              "    key[i] = C_c_string(C_u_i_car(kvpair));"
+              "    val[i] = C_c_string(C_u_i_cdr(kvpair));"
+              "}"
+              "key[len] = NULL;"
+              "val[len] = NULL;"
+              "C_return(PQconnectStartParams(key, val, 0));")
+            (map (lambda (x) (cons (string-append (->string (car x)) "\x00")
+                                   (string-append (->string (cdr x)) "\x00"))) spec)
+            (make-blob (* (add1 len) (foreign-value "sizeof(char *)" int)))
+            (make-blob (* (add1 len) (foreign-value "sizeof(char *)" int)))
+            len)))
+        (else (PQconnectStart (alist->connection-spec spec))))))
+
+(define (connect #!optional (conn-spec '())
+                 (type-parsers (default-type-parsers))
+                 (type-unparsers (default-type-unparsers)))
+  (let ((conn-ptr (connect-start conn-spec)))
+    (cond
+     ((not conn-ptr)
+      (postgresql-error
+       'internal 'connect
+       "Unable to allocate a Postgres connection structure" conn-spec))
+     ((= (foreign-value "CONNECTION_BAD" int) (PQstatus conn-ptr))
+      (let ((message (PQerrorMessage conn-ptr)))
+        (PQfinish conn-ptr)
+        (postgresql-error
+         'connect 'connect
+         (conc "Connection to Postgres database failed: " message) conn-spec)))
+     (else
+      (let ((conn (make-pg-connection conn-ptr type-parsers
+                                      (make-hash-table) type-unparsers 0)))
+        ;; We don't want libpq to piss in our stderr stream
+        ((foreign-lambda* void ((pgconn* conn))
+           "PQsetNoticeReceiver(conn, nullNoticeReceiver, NULL);") conn-ptr)
+        (wait-for-connection! conn PQconnectPoll)
+        (set-finalizer! conn disconnect)
+        ;; Retrieve type-information from PostgreSQL metadata for use by
+        ;; the various value-parsers.
+        (update-type-parsers! conn)
+        conn)))))
+
+(define (reset-connection connection)
+  (let ((conn-ptr (pg-connection-ptr connection)))
+    (if (PQresetStart conn-ptr) ;; Update oid-parsers?
+        (wait-for-connection! connection PQresetPoll)
+        (let ((error-message (PQerrorMessage conn-ptr)))
+          (disconnect connection)
+          (postgresql-error
+           'connect 'reset-connection
+           (conc "Reset of connection failed: " error-message) connection)))))
+
+(define (disconnect connection)
+  (and-let* ((conn-ptr (pg-connection-ptr connection)))
+    (pg-connection-ptr-set! connection #f)
+    (pg-connection-type-parsers-set! connection #f)
+    (pg-connection-oid-parsers-set! connection #f)
+    (PQfinish conn-ptr))
+  (void))
+
+;;;;;;;;;;;;;;;
+;;;; Results
+;;;;;;;;;;;;;;;
+
+(define-record pg-result ptr value-parsers)
+(define result? pg-result?)
+
+(define (clear-result! result)
+  (and-let* ((result-ptr (pg-result-ptr result)))
+    (pg-result-ptr-set! result #f)
+    (PQclear result-ptr)))
+
+(define (row-count result)
+  (PQntuples (pg-result-ptr result)))
+
+(define (column-count result)
+  (PQnfields (pg-result-ptr result)))
+
+;; Helper procedures for bounds checking; so we can distinguish between
+;; out of bounds and nonexistant columns, and signal it.
+(define (check-column-index! result index location)
+  (when (>= index (column-count result))
+    (postgresql-error
+     'bounds location
+     (sprintf "Result column ~A out of bounds" index) result index)))
+
+(define (check-row-index! result index location)
+  (when (>= index (row-count result))
+    (postgresql-error
+     'bounds location
+     (sprintf "Result row ~A out of bounds" index) result index)))
+
+(define (column-name result index)
+  (check-column-index! result index 'column-name)
+  (string->symbol (PQfname (pg-result-ptr result) index)))
+
+(define (column-names result)
+  (let ((ptr (pg-result-ptr result)))
+    (let loop ((names '())
+               (column (column-count result)))
+      (if (= column 0)
+          names
+          (loop (cons (string->symbol (PQfname ptr (sub1 column))) names)
+                (sub1 column))))))
+
+(define (column-index result name)
+  (let ((idx (PQfnumber (pg-result-ptr result) (symbol->string name))))
+    (and (>= idx 0) idx)))
+
+(define (table-oid result index)
+  (check-column-index! result index 'table-oid)
+  (let ((oid (PQftable (pg-result-ptr result) index)))
+    (and (not (= oid invalid-oid)) oid)))
+
+;; Fixes the off-by-1 unexpectedness in libpq/the protocol to make it more
+;; consistent with the rest of Scheme.  However, this is inconsistent with
+;; almost all other PostgreSQL interfaces...
+(define (table-column-index result index)
+  (check-column-index! result index 'table-column-index)
+  (let ((idx (PQftablecol (pg-result-ptr result) index)))
+    (and (> idx 0) (sub1 idx))))
+
+(define format-table
+  '((0 . text) (1 . binary)))
+
+(define (format->symbol format)
+  (or (alist-ref format format-table eq?)
+      (postgresql-error 'type 'format->symbol "Unknown format" format)))
+
+(define (symbol->format symbol)
+  (or (and-let* ((res (rassoc symbol format-table eq?)))
+        (car res))
+      (postgresql-error 'type 'format->symbol "Unknown format" symbol)))
+
+(define (column-format result index)
+  (check-column-index! result index 'column-format)
+  (format->symbol (PQfformat (pg-result-ptr result) index)))
+
+(define (column-type result index)
+  (check-column-index! result index 'column-type)
+  (PQftype (pg-result-ptr result) index))
+
+;; This is really not super-useful as it requires intimate knowledge
+;; about the internal implementations of types in PostgreSQL.
+(define (column-type-modifier result index)
+  (check-column-index! result index 'column-type)
+  (let ((mod (PQfmod (pg-result-ptr result) index)))
+    (and (>= mod 0) mod)))
+
+;; Unchecked version, for speed
+(define (value-at* result column row raw)
+  (let ((ptr (pg-result-ptr result)))
+    (if (PQgetisnull ptr row column)
+        (sql-null)
+        (let* ((len (PQgetlength ptr row column))
+               (fmt (PQfformat ptr column))
+               (value (case fmt
+                        ((0) (make-string len))
+                        ((1) (make-blob len))
+                        (else (postgresql-error
+                               'internal 'value-at
+                               (conc "Unknown column format type: " fmt)
+                               result column row raw)))))
+          (memcpy value (PQgetvalue-ptr ptr row column) len)
+          (if (or raw (blob? value))
+              value
+              ((vector-ref (pg-result-value-parsers result) column) value))))))
+
+(define (value-at result #!optional (column 0) (row 0) #!key raw)
+  (check-row-index! result row 'value)
+  (check-column-index! result column 'value)
+  (value-at* result column row raw))
+
+(define (row-values* result row column-count raw)
+  (let loop ((list '())
+             (column column-count))
+    (if (= column 0)
+        list
+        (loop (cons (value-at* result (sub1 column) row raw) list)
+              (sub1 column)))))
+
+(define (row-values result #!optional (row 0) #!key raw)
+  (check-row-index! result row 'row)
+  (row-values* result row (column-count result) raw))
+
+(define (column-values* result column row-count raw)
+  (let loop ((list '())
+             (row row-count))
+    (if (= row 0)
+        list
+        (loop (cons (value-at* result column (sub1 row) raw) list)
+              (sub1 row)))))
+
+(define (column-values result #!optional (column 0) #!key raw)
+  (check-column-index! result column 'column)
+  (column-values* result column (row-count result) raw))
+
+;; (define (row-alist result #!optional (row 0) #!key raw)
+;;   (map cons (column-names result) (row-values result row raw: raw)))
+(define (row-alist result #!optional (row 0) #!key raw)
+  (check-row-index! result row 'row-alist)
+  (let loop ((alist '())
+             (column (column-count result)))
+    (if (= column 0)
+        alist
+        (loop (cons (cons (string->symbol
+                           (PQfname (pg-result-ptr result) (sub1 column)))
+                          (value-at* result (sub1 column) row raw)) alist)
+              (sub1 column)))))
+
+;;; TODO: Do we want/need PQnparams and PQparamtype bindings?
+
+(define (affected-rows result)
+  (string->number (PQcmdTuples (pg-result-ptr result))))
+
+(define (inserted-oid result)
+  (let ((oid (PQoidValue (pg-result-ptr result))))
+    (and (not (= oid invalid-oid)) oid)))
+
+
+;;;;;;;;;;;;;;;;;;;;;;;;
+;;;; Query procedures
+;;;;;;;;;;;;;;;;;;;;;;;;
+
+;; Buffer all available input, yielding if nothing is available:
+(define (buffer-available-input! conn)
+  (let ((conn-ptr (pg-connection-ptr conn))
+        (conn-fd (pgsql-connection->fd conn)))
+    (let loop ()
+      (if (PQconsumeInput conn-ptr)
+          (when (PQisBusy conn-ptr)
+            (thread-wait-for-i/o! conn-fd #:input)
+            (loop))
+          (postgresql-error
+           'i/o 'buffer-available-input!
+           (conc "Error reading reply from server: " (PQerrorMessage conn-ptr))
+           conn)))))
+
+;; Here be more dragons
+(define (resolve-unknown-types! conn oids)
+  (unless (null? oids)
+    (let* ((parsers (pg-connection-oid-parsers conn))
+           (q (conc "SELECT t.oid, t.typtype, t.typelem, t.typdelim, "
+                    "       t.typbasetype, t.typarray, a.attrelid, a.atttypid "
+                    "FROM pg_type t "
+                    "     LEFT JOIN pg_attribute a "
+                    "     ON t.typrelid = a.attrelid AND a.attnum > 0 "
+                    "WHERE t.oid IN (~A)  "
+                    "ORDER BY COALESCE(t.typrelid,-1) ASC, a.attnum ASC"))
+           (result (query* conn (sprintf q (in-list (length oids)))
+                           (map number->string oids) raw: #t))
+           (count (row-count result)))
+      (let dissect-types ((unknown-oids (list))
+                          (pos 0)
+                          (domains (list))
+                          (arrays (list))
+                          (classes (list))
+                          (last-class 0))
+        (cond
+         ((>= pos count)     ; Done scanning rows?
+          ;; Keep going until all oids are resolved
+          (resolve-unknown-types! conn unknown-oids)
+          ;; Postprocessing step: resolve all nested types
+          (for-each (lambda (d)
+                      (and-let* ((p (hash-table-ref/default parsers (cdr d) #f)))
+                        (hash-table-set! parsers (car d) p)))
+                    domains)
+          (for-each (lambda (a)
+                      (and-let* ((p (hash-table-ref/default parsers (cddr a) #f)))
+                        (hash-table-set! parsers (car a)
+                                         (make-array-parser p (cadr a)))))
+                    arrays)
+          (for-each
+           (lambda (c)
+             (and-let* ((p-list
+                         (fold
+                          (lambda (att l)
+                            (and-let* ((l)
+                                       (p (hash-table-ref/default parsers att #f)))
+                              (cons p l)))
+                          '()
+                          (cdr c))))
+               (hash-table-set! parsers (car c)
+                                (make-composite-parser p-list))))
+           classes))
+         ((not (string=? (value-at* result 4 pos #f) "0")) ; Domain type?
+          (let* ((basetype-oid (string->number (value-at* result 4 pos #f)))
+                 (parser (hash-table-ref/default parsers basetype-oid #f))
+                 (oid (string->number (value-at* result 0 pos #f))))
+            (dissect-types (if parser
+                               unknown-oids
+                               (cons basetype-oid unknown-oids))
+                           (add1 pos) (cons (cons oid basetype-oid) domains)
+                           arrays classes last-class)))
+         ((string=? (value-at* result 5 pos #f) "0") ; Array value?
+          (let* ((elem (string->number (value-at* result 2 pos #f)))
+                 (delim (string-ref (value-at* result 3 pos #f) 0))
+                 (parser (hash-table-ref/default parsers elem #f))
+                 (oid (string->number (value-at* result 0 pos #f))))
+            (dissect-types (if parser
+                               unknown-oids
+                               (cons elem unknown-oids))
+                           (add1 pos) domains
+                           (cons (cons oid (cons delim elem)) arrays)
+                           classes last-class)))
+         ((string=? (value-at* result 1 pos #f) "c") ; Class? (i.e., table or type)
+          (let* ((classid (string->number (value-at* result 6 pos #f)))
+                 (attrid (string->number (value-at* result 7 pos #f)))
+                 (parser (hash-table-ref/default parsers attrid #f)))
+            (dissect-types (if parser
+                               unknown-oids
+                               (cons attrid unknown-oids))
+                           (add1 pos) domains arrays
+                           ;; Keep oid at the front of the list, insert this
+                           ;; attr after it, before the other attrs, if any.
+                           (if (= last-class classid)
+                               (cons (cons (caar classes)
+                                           (cons attrid (cdar classes)))
+                                     (cdr classes))
+                               (cons (cons (string->number
+                                            (value-at* result 0 pos #f))
+                                           (list attrid)) classes))
+                           classid)))
+         (else
+          (dissect-types unknown-oids (add1 pos)
+                         domains arrays classes last-class)))))))
+
+(define (make-value-parsers conn pqresult #!key raw)
+  (let* ((nfields (PQnfields pqresult))
+         (parsers (make-vector nfields))
+         (ht (pg-connection-oid-parsers conn)))
+    (let loop ((col 0)
+               (unknowns (list)))
+      (if (= col nfields)
+          (begin
+            (resolve-unknown-types! conn (map cdr unknowns))
+            (for-each (lambda (unknown)
+                        (let* ((col (car unknown))
+                               (oid (cdr unknown))
+                               (parser (hash-table-ref/default ht oid identity)))
+                          (vector-set! parsers col parser)))
+                      unknowns)
+            parsers)
+          (let* ((oid (PQftype pqresult col))
+                 (parser (if raw identity (hash-table-ref/default ht oid #f))))
+            (vector-set! parsers col parser)
+            (loop (add1 col) (if parser
+                                 unknowns
+                                 (cons (cons col oid) unknowns))))))))
+
+;; Collect the result pointers from the last query.
+;;
+;; A pgresult represents an entire resultset and is always read into memory
+;; all at once.
+(define (get-last-result conn #!key raw)
+  (buffer-available-input! conn)
+  (let* ((conn-ptr (pg-connection-ptr conn))
+         ;; Read out all remaining results (including the current one).
+         ;; TODO: Is this really needed? libpq does it (in pqExecFinish),
+         ;; but ostensibly only to concatenate the error messages for
+         ;; each query.  OTOH, maybe we want to do that, too.
+         (clean-results! (lambda (result)
+                           (let loop ((result result))
+                             (when result
+                               (PQclear result)
+                               (loop (PQgetResult conn-ptr))))))
+         (result (PQgetResult conn-ptr))
+         (status (PQresultStatus result)))
+    (cond
+     ((not result) (postgresql-error
+                    'internal 'get-last-result
+                    "Internal error! No result object available from server"
+                    conn))
+     ((member status (list PGRES_BAD_RESPONSE PGRES_FATAL_ERROR
+                           PGRES_NONFATAL_ERROR))
+      (let* ((error-field (lambda (f) (and f (PQresultErrorField result f))))
+             (error-field/int (lambda (f)
+                                (and-let* ((value (error-field f)))
+                                  (string->number value))))
+             (sqlstate (error-field PG_DIAG_SQLSTATE))
+             (maybe-severity (error-field PG_DIAG_SEVERITY))
+             (condition
+              (make-pg-condition
+               (make-property-condition
+                'query
+                'severity (and maybe-severity
+                               (string->symbol
+                                (string-downcase maybe-severity)))
+                'error-class        (and sqlstate (string-take sqlstate 2))
+                'error-code         sqlstate
+                'message-primary    (error-field PG_DIAG_MESSAGE_PRIMARY)
+                'message-detail     (error-field PG_DIAG_MESSAGE_DETAIL)
+                'message-hint       (error-field PG_DIAG_MESSAGE_HINT)
+                'statement-position (error-field/int PG_DIAG_STATEMENT_POSITION)
+                'context            (error-field PG_DIAG_CONTEXT)
+                'source-file        (error-field PG_DIAG_SOURCE_FILE)
+                'source-line        (error-field/int PG_DIAG_SOURCE_LINE)
+                'source-function    (error-field PG_DIAG_SOURCE_FUNCTION)
+                'internal-query     (error-field PG_DIAG_INTERNAL_QUERY)
+                'internal-position  (error-field/int PG_DIAG_INTERNAL_POSITION)
+                'schema-name        (error-field PG_DIAG_SCHEMA_NAME)
+                'table-name         (error-field PG_DIAG_TABLE_NAME)
+                'column-name        (error-field PG_DIAG_COLUMN_NAME)
+                'datatype-name      (error-field PG_DIAG_DATATYPE_NAME)
+                'constraint-name    (error-field PG_DIAG_CONSTRAINT_NAME))
+               'get-last-result
+               (PQresultErrorMessage result))))
+        (clean-results! result)
+        (signal condition)))
+     ((member status (list PGRES_COPY_OUT PGRES_COPY_IN))
+      ;; These are weird; A COPY puts the connection in "copy mode".
+      ;; As long as it's in "copy mode", pqgetresult will return the
+      ;; same result every time you call it, so don't try to call
+      ;; clean-results!
+      (let ((result-obj (make-pg-result result #f)))
+        (set-finalizer! result-obj clear-result!)
+        result-obj))
+     ((member status (list PGRES_EMPTY_QUERY PGRES_COMMAND_OK PGRES_TUPLES_OK))
+      (let ((result-obj (make-pg-result result #f)))
+        (set-finalizer! result-obj clear-result!)
+        (let ((trailing-result (PQgetResult conn-ptr)))
+          (when trailing-result
+            (clean-results! trailing-result)
+            (postgresql-error 'internal 'get-last-result
+                              (conc "Internal error! Unexpected extra "
+                                    "results after first query result")
+                              conn)))
+        (pg-result-value-parsers-set!
+         result-obj (make-value-parsers conn result raw: raw))
+        result-obj))
+     (else
+      (postgresql-error 'internal 'get-last-result
+                        (conc "Internal error! Unknown status code: " status)
+                        conn)))))
+
+(define (query conn query . params)
+  (query* conn query params))
+
+(define (query* conn query #!optional (params '()) #!key (format 'text) raw)
+  (let* ((params ;; Check all params and ensure they are proper pairs
+          (map (lambda (p)
+                 (let ((obj (if raw p (scheme-value->db-value conn p))))
+                   (cond ((string? obj) ; Convert to ASCIIZ
+                          (let* ((len (##sys#size obj))
+                                 (res (string-append obj "\x00")))
+                            (vector 0 len res)))
+                         ((blob? obj)
+                          (vector 1 (##sys#size obj) obj))
+                         ((sql-null? obj) #f)
+                         (else (postgresql-error
+                                'type 'query*
+                                (sprintf "Param value is not string, sql-null or blob: ~S" p)
+                                conn query params format)))))
+               params))
+         ;; It's a shame we need to traverse params twice (and again in C)...
+         (len (length params))
+         (send-query
+          (foreign-lambda*
+              bool ((pgconn* conn) (nonnull-c-string query)
+                    (bool is_prepped) (int num) (scheme-object params)
+                    (scheme-pointer valsbuf) (scheme-pointer lensbuf)
+                    (scheme-pointer fmtsbuf) (int rfmt))
+            "int i = 0, *lens = (int *)lensbuf, *fmts = (int *)fmtsbuf;"
+            "const char **vals = (const char **)valsbuf;"
+            "C_word obj, cons;"
+            "for (i=0,cons=params; i < num; ++i,cons=C_u_i_cdr(cons)) {"
+            "    obj = C_u_i_car(cons);"
+            "    if (obj == C_SCHEME_FALSE) {"
+            "        fmts[i] = lens[i] = 0;"
+            "        vals[i] = NULL;"
+            "    } else {"
+            "        fmts[i] = C_unfix(C_block_item(obj, 0));"
+            "        lens[i] = C_unfix(C_block_item(obj, 1));"
+            "        vals[i] = C_c_string(C_block_item(obj, 2));"
+            "    }"
+            "}"
+            "if (is_prepped)"
+            "  C_return(PQsendQueryPrepared((PGconn *)conn, query, num,"
+            "                               vals, lens, fmts, rfmt));"
+            "else"
+            "  C_return(PQsendQueryParams((PGconn *)conn, query, num, NULL,"
+            "                             vals, lens, fmts, rfmt));"))
+         (query-as-string (if (symbol? query) (symbol->string query) query)))
+    ;; XXX: What if we're using a newer protocol version?  Then this error is
+    ;; well-meaning but completely wrong...  Unfortunately the error message
+    ;; returned by the server if we exceed this limit is even more confusing.
+    (cond ((> len 65535)
+           (postgresql-error
+            'domain 'query*
+            (sprintf "Too many bind parameters (PG protocol supports up to 65535, but got ~A).  Try using the COPY support, or escaping the data and sending it as a big string." len)
+            conn query params format))
+          ((send-query (pg-connection-ptr conn) query-as-string (symbol? query)
+                       len params
+                       ;; We allocate here instead of in C to keep things simple
+                       (make-blob (* len (foreign-value "sizeof(char *)" int)))
+                       (make-blob (* len (foreign-value "sizeof(int)" int)))
+                       (make-blob (* len (foreign-value "sizeof(int)" int)))
+                       (symbol->format format))
+           (get-last-result conn raw: raw))
+          (else (postgresql-error 'i/o 'query*
+                                  (conc "Unable to send query to server: "
+                                        (PQerrorMessage (pg-connection-ptr conn)))
+                                  conn query params format)))))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;; Transaction management
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (with-transaction conn thunk #!key isolation access)
+  (let* ((old-depth (pg-connection-transaction-depth conn))
+         (isolation (and isolation
+                         (case isolation
+                           ((read-committed) "ISOLATION LEVEL READ COMMITTED")
+                           ((serializable) "ISOLATION LEVEL SERIALIZABLE")
+                           (else (postgresql-error
+                                  'type 'with-transaction
+                                  "Unknown isolation level" isolation)))))
+         (access (and access
+                      (case access
+                        ((read/write) "READ WRITE")
+                        ((read-only) "READ ONLY")
+                        (else (postgresql-error
+                               'type 'with-transaction
+                               "Unknown access mode" access)))))
+         (characteristics (conc (or isolation "") " " (or access "")))
+         (rollback!
+          (lambda ()
+            (if (zero? old-depth)
+                (query conn "ROLLBACK")
+                ;; We do not *need* to give savepoints unique names,
+                ;; but it aids debugging and we know the depth anyway.
+                (query conn (conc "ROLLBACK TO SAVEPOINT s_" old-depth)))))
+         (commit!
+          (lambda ()
+            (if (zero? old-depth)
+                (query conn "COMMIT")
+                (query conn (conc "RELEASE SAVEPOINT s_" old-depth))))))
+    (when (and isolation (not (zero? old-depth)))
+      (postgresql-error
+       'domain 'with-transaction
+       "Can't set isolation level in nested transactions" isolation))
+    (if (zero? old-depth)
+        (query conn (conc "BEGIN " characteristics))
+        (begin (query conn (conc "SAVEPOINT s_" old-depth))
+               ;; XXX: This should probably be SET LOCAL instead of SET
+               ;; (which is implicitly the same as SET SESSION), but I
+               ;; can't come up with a testcase that fails with this and
+               ;; succeeds with SET LOCAL, so keep it around for now.
+               (when access
+                 (query conn (conc "SET TRANSACTION " characteristics)))))
+    (pg-connection-transaction-depth-set! conn (add1 old-depth))
+    ;; TODO: Add a warning mechanism (using dynamic-wind) for when the
+    ;; user tries to jump into/out of transactions with continuations?
+    (handle-exceptions exn
+        (begin
+          (pg-connection-transaction-depth-set! conn old-depth)
+          (rollback!)
+          (raise exn))
+      (let ((res (thunk)))
+        (pg-connection-transaction-depth-set! conn old-depth)
+        (if res (commit!) (rollback!))
+        res))))
+
+(define (in-transaction? conn)
+  (> (pg-connection-transaction-depth conn) 0))
+
+;;;;;;;;;;;;;;;;;;;;
+;;;; COPY support
+;;;;;;;;;;;;;;;;;;;;
+
+(define (put-copy-data conn data)
+  (let* ((data (cond
+                ((or (string? data) (blob? data)) data)
+                ((srfi-4-vector? data) (##sys#slot data 1))
+                (else (postgresql-error
+                       'type 'put-copy-data
+                       "Expected a blob, string or srfi-4 vector" conn data))))
+         (len (##sys#size data))
+         (conn-ptr (pg-connection-ptr conn))
+         (conn-fd (pgsql-connection->fd conn)))
+    (let loop ((res (PQputCopyData conn-ptr data len)))
+      (cond
+       ((= res 0)
+        (thread-wait-for-i/o! conn-fd #:output)
+        (loop (PQputCopyData conn-ptr data len)))
+       ((= res 1) (void))
+       ((= res -1)
+        (postgresql-error
+         'i/o 'put-copy-data
+         (conc "Error putting COPY data: " (PQerrorMessage conn-ptr)) conn))
+       (else (postgresql-error
+              'internal 'put-copy-data
+              (conc "Internal error! Unexpected return value: " res) conn))))))
+
+(define (put-copy-end conn #!optional error-message)
+  (let ((conn-ptr (pg-connection-ptr conn))
+        (conn-fd (pgsql-connection->fd conn)))
+    (let loop ((res (PQputCopyEnd conn-ptr error-message)))
+      (cond
+       ((= res 0)
+        (thread-wait-for-i/o! conn-fd #:output)
+        (loop (PQputCopyEnd conn-ptr error-message)))
+       ((= res 1) (get-last-result conn))
+       ((= res -1)
+        (postgresql-error
+         'i/o 'put-copy-end
+         (conc "Error ending put COPY data: " (PQerrorMessage conn-ptr))
+         conn error-message))
+       (else
+        (postgresql-error
+         'internal 'put-copy-end
+         (conc "Internal error! Unexpected return value: " res) conn))))))
+
+(define (get-copy-data conn #!key (format 'text))
+  (let ((conn-ptr (pg-connection-ptr conn)))
+    (let loop ()
+      (let-location ((buf c-pointer))
+        (let ((res (PQgetCopyData conn-ptr (location buf) #t)))
+          (cond
+           ((> res 0)
+            (let ((value (case format
+                           ((text) (make-string res))
+                           ((binary) (make-blob res))
+                           (else (postgresql-error
+                                  'internal 'get-copy-data
+                                  (conc "Unknown column format type: " format)
+                                  conn)))))
+              (memcpy value buf res)
+              (free buf)
+              value))
+           ((= res 0)
+            (buffer-available-input! conn)
+            (loop))
+           ((= res -1)
+            (get-last-result conn))
+           ((= res -2)
+            (postgresql-error
+             'i/o 'get-copy-data
+             (conc "Error getting COPY data: " (PQerrorMessage conn-ptr)) conn))
+           (else (postgresql-error
+                  'internal 'get-copy-data
+                  (conc "Internal error! Unexpected return value: " res)
+                  conn))))))))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;; Value escaping and quotation
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (escape-string conn str)
+  (define %escape-string-conn
+    (foreign-lambda size_t PQescapeStringConn
+      pgconn* scheme-pointer scheme-pointer size_t (c-pointer bool)))
+  (let-location ((err bool))
+    (let* ((strlen (string-length str))
+           (buflen (add1 (* strlen 2)))
+           (buffer (make-string buflen))
+           (conn-ptr (pg-connection-ptr conn))
+           (size (%escape-string-conn conn-ptr buffer str strlen (location err))))
+      (cond (err (postgresql-error 'internal 'escape-string
+                                   (conc "String escaping failed. "
+                                         (PQerrorMessage conn-ptr)) conn str))
+            ((= size buflen) buffer)
+            (else (##sys#substring buffer 0 size))))))
+
+(define (quote-identifier conn str)
+  (cond-expand
+    (has-escape-identifier
+     (define %escape-ident
+       (foreign-lambda c-string* PQescapeIdentifier pgconn* scheme-pointer size_t))
+     (or (%escape-ident (pg-connection-ptr conn) str (string-length str))
+         (postgresql-error 'internal 'quote-identifier
+                           (conc "Identifier escaping failed: "
+                                 (PQerrorMessage (pg-connection-ptr conn)))
+                           conn str)))
+    (else (postgresql-error 'unsupported-version 'quote-identifier
+                            (conc "Please upgrade your PostgreSQL to 9.0 or later "
+                                  "in order to be able to use quote-identifier!")
+                            conn str))))
+
+(define (escape-bytea conn obj)
+  (define %escape-bytea-conn
+    (foreign-lambda (c-pointer unsigned-char) PQescapeByteaConn
+      pgconn* scheme-pointer size_t (c-pointer size_t)))
+  (let-location ((allocated size_t))
+    (let* ((data (cond ((or (string? obj) (blob? obj)) obj)
+                       ((srfi-4-vector? obj) (##sys#slot obj 1))
+                       (else (postgresql-error
+                              'type 'escape-bytea
+                              "Expected string, blob or srfi-4 vector" obj))))
+           (conn-ptr (pg-connection-ptr conn))
+           (buf (%escape-bytea-conn
+                 conn-ptr data (##sys#size data) (location allocated))))
+      (if buf
+          (let* ((string-length (sub1 allocated))
+                 (result-string (make-string string-length)))
+            (memcpy result-string buf string-length)
+            (free buf)
+            result-string)
+          (postgresql-error
+           'internal 'escape-bytea
+           (conc "Byte array escaping failed: " (PQerrorMessage conn-ptr))
+           conn obj)))))
+
+(define (unescape-bytea str)
+  (define %unescape-bytea
+    (foreign-lambda (c-pointer unsigned-char) PQunescapeBytea c-string (c-pointer size_t)))
+  (let-location ((blob-length size_t))
+    (let ((buf (%unescape-bytea str (location blob-length))))
+      (if buf 
+          (let ((result-blob (make-blob blob-length)))
+            (memcpy result-blob buf blob-length)
+            (free buf)
+            (blob->u8vector/shared result-blob))
+          (postgresql-error 'internal 'unescape-bytea
+                            "Byte array unescaping failed (out of memory?)" str)))))
+
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;; High-level interface
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (make-result-fold item-count sub-item-count extract-item)
+  (lambda (kons knil result)
+    (let ((items (item-count result))
+          (sub-items (sub-item-count result)))
+      (let loop ((seed knil)
+                 (item 0))
+        (if (= item items)
+            seed
+            (loop (kons (extract-item result item sub-items #f) seed) (add1 item)))))))
+
+(define row-fold (make-result-fold row-count column-count row-values*))
+(define (row-fold* kons knil result)
+  (row-fold (lambda (values seed)
+              (apply kons (append values (list seed)))) knil result))
+
+(define column-fold (make-result-fold column-count row-count column-values*))
+(define (column-fold* kons knil result)
+  (column-fold (lambda (values seed)
+                 (apply kons (append values (list seed)))) knil result))
+
+
+(define (make-result-fold-right item-count sub-item-count extract-item)
+  (lambda (kons knil result)
+    (let ((sub-items (sub-item-count result)))
+      (let loop ((seed knil)
+                 (item (item-count result)))
+        (if (= item 0)
+            seed
+            (loop (kons (extract-item result (sub1 item) sub-items #f) seed) (sub1 item)))))))
+
+(define row-fold-right (make-result-fold-right row-count column-count row-values*))
+(define (row-fold-right* kons knil result)
+  (row-fold-right (lambda (values seed)
+                    (apply kons (append values (list seed)))) knil result))
+
+(define column-fold-right (make-result-fold-right column-count row-count column-values*))
+(define (column-fold-right* kons knil result)
+  (column-fold-right (lambda (values seed)
+                       (apply kons (append values (list seed)))) knil result))
+
+
+(define (row-for-each proc result)
+  (row-fold (lambda (values seed) (proc values)) #f result)
+  (void))
+(define (row-for-each* proc result)
+  (row-fold (lambda (values seed) (apply proc values)) #f result)
+  (void))
+
+(define (column-for-each proc result)
+  (column-fold (lambda (values seed) (proc values)) #f result)
+  (void))
+(define (column-for-each* proc result)
+  (column-fold (lambda (values seed) (apply proc values)) #f result)
+  (void))
+
+;; Like regular Scheme map, the order in which the procedure is applied is
+;; undefined.  We make good use of that by traversing the resultset from
+;; the end back to the beginning, thereby avoiding a reverse! on the result.
+(define (row-map proc res)
+  (row-fold-right (lambda (row lst) (cons (proc row) lst)) '() res))
+(define (row-map* proc res)
+  (row-fold-right (lambda (row lst) (cons (apply proc row) lst)) '() res))
+(define (column-map proc res)
+  (column-fold-right (lambda (col lst) (cons (proc col) lst)) '() res))
+(define (column-map* proc res)
+  (column-fold-right (lambda (col lst) (cons (apply proc col) lst)) '() res))
+
+(define (result-format result)
+  (if (and result ((foreign-lambda bool PQbinaryTuples pgresult*)
+                   (pg-result-ptr result)))
+      'binary 'text))
+
+(define (copy-query*-fold kons knil conn query
+                          #!optional (params '()) #!key (format 'text) raw)
+  (let* ((result (query* conn query params format: format raw: raw))
+         (data-format (result-format result)))
+    (handle-exceptions exn
+        (let cleanup () (if (result? (get-copy-data conn)) (raise exn) (cleanup)))
+      (let loop ((data (get-copy-data conn format: data-format))
+                 (seed knil))
+        (if (result? data)
+            seed
+            ;; Explicit ordering; data could be _very_ big, allow one to be GCed
+            (let ((next (kons data seed)))
+              (loop (get-copy-data conn format: data-format) next)))))))
+
+(define (copy-query-fold kons knil conn query . params)
+  (copy-query*-fold kons knil conn query params))
+
+
+;; This is slow and memory-intensive if data is big. Provided for completeness
+(define (copy-query*-fold-right kons knil conn query
+                                #!optional (params '()) #!key (format 'text) raw)
+  (let* ((result (query* conn query params format: format raw: raw))
+         (data-format (result-format result)))
+    (handle-exceptions exn
+        (let cleanup () (if (result? (get-copy-data conn)) (raise exn) (cleanup)))
+      (let loop ((data (get-copy-data conn format: data-format)))
+        (if (result? data)
+            knil
+            (kons data (loop (get-copy-data conn format: data-format))))))))
+
+(define (copy-query-fold-right kons knil conn query . params)
+  (copy-query*-fold-right kons knil conn query params))
+
+
+(define (copy-query*-map proc conn query
+                         #!optional (params '()) #!key (format 'text) raw)
+  (reverse! (copy-query*-fold (lambda (data seed) (cons (proc data) seed))
+                              '() conn query params format: format raw: raw)))
+
+(define (copy-query-map proc conn query . params)
+  (copy-query*-map proc conn query params))
+
+
+(define (copy-query*-for-each proc conn query
+                              #!optional (params '()) #!key (format 'text) raw)
+  (copy-query*-fold (lambda (data seed) (proc data))
+                    #f conn query params format: format raw: raw)
+  (void))
+
+(define (copy-query-for-each proc conn query . params)
+  (copy-query*-for-each proc conn query params))
+
+;; A bit of a weird name but consistent
+(define (call-with-output-copy-query*
+         proc conn query #!optional (params '()) #!key (format 'text) raw)
+  (query* conn query params format: format raw: raw)
+  (let* ((closed? #f)
+         (output-port (make-output-port
+                       (lambda (data) (put-copy-data conn data))
+                       (lambda () (put-copy-end conn) (set! closed? #t)))))
+    (handle-exceptions exn
+        (if closed?
+            (raise exn)
+            (handle-exceptions _
+                (raise exn)
+              ;; Previously written data will be discarded to guarantee atomicity
+              (put-copy-end conn "Chicken PostgreSQL egg -- forcing error")))
+      (call-with-values (lambda () (proc output-port))
+        (lambda args
+          (unless closed? (put-copy-end conn))
+          (apply values args))))))
+
+(define (call-with-output-copy-query proc conn query . params)
+  (call-with-output-copy-query* proc conn query params))
+
+(define (with-output-to-copy-query*
+         thunk conn query #!optional (params '()) #!key (format 'text) raw)
+  (call-with-output-copy-query* (lambda (x) (with-output-to-port x thunk))
+                                conn query params format: format raw: raw))
+
+(define (with-output-to-copy-query thunk conn query . params)
+  (with-output-to-copy-query* thunk conn query params))
+
+)