From 33f0108df8a79cdb6dbf91f7eb4329143c0730d8 Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Mon, 30 Dec 2002 15:31:51 +0000 Subject: [PATCH] Cause FETCH 1 to return the current cursor row, or zero if at beginning/end of cursor. Have MOVE return 0/1 depending on cursor position. Matches SQL spec. Pass cursor counter from parser as a long rather than int. Doc updates. --- doc/src/sgml/ref/fetch.sgml | 28 ++----------------- doc/src/sgml/ref/move.sgml | 6 ++-- src/backend/commands/portalcmds.c | 46 +++++++++++++++++++++++++++---- src/backend/parser/gram.y | 21 ++++---------- src/backend/tcop/utility.c | 4 +-- src/include/commands/portalcmds.h | 4 +-- src/include/nodes/parsenodes.h | 4 +-- 7 files changed, 56 insertions(+), 57 deletions(-) diff --git a/doc/src/sgml/ref/fetch.sgml b/doc/src/sgml/ref/fetch.sgml index fae7ab5ba2..b08ad4a191 100644 --- a/doc/src/sgml/ref/fetch.sgml +++ b/doc/src/sgml/ref/fetch.sgml @@ -1,5 +1,5 @@ @@ -89,7 +89,7 @@ FETCH [ FORWARD | BACKWARD | RELATIVE ] [ # A signed integer that specifies how many rows to fetch. Note that a negative integer is equivalent to changing the sense of - FORWARD and BACKWARD. + FORWARD and BACKWARD. Zero re-fetches the current row. @@ -180,30 +180,6 @@ WARNING: FETCH/ABSOLUTE not supported, using RELATIVE - - -ERROR: FETCH/RELATIVE at current position is not supported - - - - SQL92 allows one to repetitively retrieve the cursor - at its current position using the syntax - -FETCH RELATIVE 0 FROM cursor. - - - - - PostgreSQL does not currently support - this notion; in fact the value zero is reserved to indicate that - all rows should be retrieved and is equivalent to specifying the ALL keyword. - If the RELATIVE keyword has been used, PostgreSQL - assumes that the user intended SQL92 behavior - and returns this error message. - - - - diff --git a/doc/src/sgml/ref/move.sgml b/doc/src/sgml/ref/move.sgml index 46c830406e..5d4f1c8309 100644 --- a/doc/src/sgml/ref/move.sgml +++ b/doc/src/sgml/ref/move.sgml @@ -1,5 +1,5 @@ @@ -35,8 +35,8 @@ MOVE [ direction ] Description - MOVE allows a user to move cursor position a specified - number of rows. + MOVE allows a user to move the cursor position a + specified number of rows. MOVE works like the FETCH command, but only positions the cursor and does not return rows. LAST moves to the end diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c index b1799e49f8..3a670d8f89 100644 --- a/src/backend/commands/portalcmds.c +++ b/src/backend/commands/portalcmds.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/commands/portalcmds.c,v 1.6 2002/12/15 16:17:42 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/commands/portalcmds.c,v 1.7 2002/12/30 15:31:47 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -65,7 +65,7 @@ PortalCleanup(Portal portal) void PerformPortalFetch(char *name, bool forward, - int count, + long count, CommandDest dest, char *completionTag) { @@ -100,14 +100,48 @@ PerformPortalFetch(char *name, return; } - /* If zero count, we are done */ + /* If zero count, handle specially */ if (count == 0) - return; + { + bool on_row = false; + + /* Are we sitting on a row? */ + oldcontext = MemoryContextSwitchTo(PortalGetHeapMemory(portal)); + queryDesc = PortalGetQueryDesc(portal); + estate = queryDesc->estate; + if (portal->atStart == false && portal->atEnd == false) + on_row = true; + MemoryContextSwitchTo(oldcontext); + + if (dest == None) + { + /* MOVE 0 returns 0/1 based on if FETCH 0 would return a row */ + if (completionTag && on_row) + strcpy(completionTag, "MOVE 1"); + return; + } + else + { + /* If we are not on a row, FETCH 0 returns nothing */ + if (!on_row) + return; + + /* Since we are sitting on a row, return the row */ + /* Back up so we can reread the row */ + PerformPortalFetch(name, false /* backward */, 1, + None, /* throw away output */ + NULL /* do not modify the command tag */); + + /* Set up to fetch one row */ + count = 1; + forward = true; + } + } /* Internally, zero count processes all portal rows */ - if (count == INT_MAX) + if (count == LONG_MAX) count = 0; - + /* * switch into the portal context */ diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index bb94d1f8e8..c19673fc42 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -11,7 +11,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.388 2002/12/12 20:35:13 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.389 2002/12/30 15:31:47 momjian Exp $ * * HISTORY * AUTHOR DATE MAJOR EVENT @@ -2591,13 +2591,6 @@ comment_text: FetchStmt: FETCH direction fetch_how_many from_in name { FetchStmt *n = makeNode(FetchStmt); - if ($2 == RELATIVE) - { - if ($3 == 0) - elog(ERROR, - "FETCH / RELATIVE at current position is not supported"); - $2 = FORWARD; - } if ($3 < 0) { $3 = -$3; @@ -2629,10 +2622,6 @@ FetchStmt: FETCH direction fetch_how_many from_in name | FETCH direction from_in name { FetchStmt *n = makeNode(FetchStmt); - if ($2 == RELATIVE) - { - $2 = FORWARD; - } n->direction = $2; n->howMany = 1; n->portalname = $4; @@ -2719,20 +2708,20 @@ FetchStmt: FETCH direction fetch_how_many from_in name direction: FORWARD { $$ = FORWARD; } | BACKWARD { $$ = BACKWARD; } - | RELATIVE { $$ = RELATIVE; } + | RELATIVE { $$ = FORWARD; } | ABSOLUTE { elog(NOTICE, "FETCH / ABSOLUTE not supported, using RELATIVE"); - $$ = RELATIVE; + $$ = FORWARD; } ; fetch_how_many: Iconst { $$ = $1; } | '-' Iconst { $$ = - $2; } - | ALL { $$ = INT_MAX; } - | LAST { $$ = INT_MAX; } + | ALL { $$ = LONG_MAX; } + | LAST { $$ = LONG_MAX; } | NEXT { $$ = 1; } | PRIOR { $$ = -1; } ; diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c index 40228601d7..cc0f139b2d 100644 --- a/src/backend/tcop/utility.c +++ b/src/backend/tcop/utility.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/tcop/utility.c,v 1.185 2002/12/06 05:00:31 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/tcop/utility.c,v 1.186 2002/12/30 15:31:48 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -257,7 +257,7 @@ ProcessUtility(Node *parsetree, FetchStmt *stmt = (FetchStmt *) parsetree; char *portalName = stmt->portalname; bool forward; - int count; + long count; forward = (bool) (stmt->direction == FORWARD); diff --git a/src/include/commands/portalcmds.h b/src/include/commands/portalcmds.h index 5526ac997d..d143423f6a 100644 --- a/src/include/commands/portalcmds.h +++ b/src/include/commands/portalcmds.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $Id: portalcmds.h,v 1.3 2002/11/13 00:44:09 momjian Exp $ + * $Id: portalcmds.h,v 1.4 2002/12/30 15:31:50 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -25,7 +25,7 @@ * BadArg if forward invalid. * "ERROR" if portal not found. */ -extern void PerformPortalFetch(char *name, bool forward, int count, +extern void PerformPortalFetch(char *name, bool forward, long count, CommandDest dest, char *completionTag); /* diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index c409ec7ea8..0f9b7613a0 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $Id: parsenodes.h,v 1.223 2002/12/12 20:35:16 tgl Exp $ + * $Id: parsenodes.h,v 1.224 2002/12/30 15:31:51 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -1198,7 +1198,7 @@ typedef struct FetchStmt { NodeTag type; int direction; /* FORWARD or BACKWARD */ - int howMany; /* amount to fetch */ + long howMany; /* amount to fetch */ char *portalname; /* name of portal (cursor) */ bool ismove; /* TRUE if MOVE */ } FetchStmt;