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Restructure parsetree representation of DECLARE CURSOR: now it's a

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utility statement (DeclareCursorStmt) with a SELECT query dangling from
it, rather than a SELECT query with a few unusual fields in it.  Add
code to determine whether a planned query can safely be run backwards.
If DECLARE CURSOR specifies SCROLL, ensure that the plan can be run
backwards by adding a Materialize plan node if it can't.  Without SCROLL,
you get an error if you try to fetch backwards from a cursor that can't
handle it.  (There is still some discussion about what the exact
behavior should be, but this is necessary infrastructure in any case.)
Along the way, make EXPLAIN DECLARE CURSOR work.
This commit is contained in:
Tom Lane
2003-03-10 03:53:52 +00:00
parent b9e8ffcd5d
commit aa83bc04e0
40 changed files with 664 additions and 574 deletions
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90
src/backend/parser/analyze.c
View File

@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/src/backend/parser/analyze.c,v 1.264 2003/02/13 22:50:01 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/analyze.c,v 1.265 2003/03/10 03:53:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -96,6 +96,8 @@ static Query *transformSelectStmt(ParseState *pstate, SelectStmt *stmt);
static Query *transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt);
static Node *transformSetOperationTree(ParseState *pstate, SelectStmt *stmt);
static Query *transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt);
static Query *transformDeclareCursorStmt(ParseState *pstate,
DeclareCursorStmt *stmt);
static Query *transformPrepareStmt(ParseState *pstate, PrepareStmt *stmt);
static Query *transformExecuteStmt(ParseState *pstate, ExecuteStmt *stmt);
static Query *transformCreateStmt(ParseState *pstate, CreateStmt *stmt,
@@ -313,6 +315,11 @@ transformStmt(ParseState *pstate, Node *parseTree,
(SelectStmt *) parseTree);
break;
case T_DeclareCursorStmt:
result = transformDeclareCursorStmt(pstate,
(DeclareCursorStmt *) parseTree);
break;
default:
/*
@@ -445,7 +452,7 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt,
Assert(IsA(selectQuery, Query));
Assert(selectQuery->commandType == CMD_SELECT);
if (selectQuery->into || selectQuery->isPortal)
if (selectQuery->into)
elog(ERROR, "INSERT ... SELECT may not specify INTO");
/*
@@ -1616,27 +1623,6 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
qry->commandType = CMD_SELECT;
if (stmt->portalname)
{
/* DECLARE CURSOR */
if (stmt->into)
elog(ERROR, "DECLARE CURSOR must not specify INTO");
if (stmt->forUpdate)
elog(ERROR, "DECLARE/UPDATE is not supported"
"\n\tCursors must be READ ONLY");
qry->into = makeNode(RangeVar);
qry->into->relname = stmt->portalname;
qry->isPortal = TRUE;
qry->isBinary = stmt->binary; /* internal portal */
}
else
{
/* SELECT */
qry->into = stmt->into;
qry->isPortal = FALSE;
qry->isBinary = FALSE;
}
/* make FOR UPDATE clause available to addRangeTableEntry */
pstate->p_forUpdate = stmt->forUpdate;
@@ -1646,6 +1632,8 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
/* transform targetlist */
qry->targetList = transformTargetList(pstate, stmt->targetList);
/* handle any SELECT INTO/CREATE TABLE AS spec */
qry->into = stmt->into;
if (stmt->intoColNames)
applyColumnNames(qry->targetList, stmt->intoColNames);
@@ -1708,8 +1696,6 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
SetOperationStmt *sostmt;
RangeVar *into;
List *intoColNames;
char *portalname;
bool binary;
List *sortClause;
Node *limitOffset;
Node *limitCount;
@@ -1738,14 +1724,10 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
leftmostSelect->larg == NULL);
into = leftmostSelect->into;
intoColNames = leftmostSelect->intoColNames;
portalname = stmt->portalname;
binary = stmt->binary;
/* clear them to prevent complaints in transformSetOperationTree() */
leftmostSelect->into = NULL;
leftmostSelect->intoColNames = NIL;
stmt->portalname = NULL;
stmt->binary = false;
/*
* These are not one-time, exactly, but we want to process them here
@@ -1825,36 +1807,13 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
}
/*
* Insert one-time items into top-level query
* Handle SELECT INTO/CREATE TABLE AS.
*
* This needs to agree with transformSelectStmt!
*/
if (portalname)
{
/* DECLARE CURSOR */
if (into)
elog(ERROR, "DECLARE CURSOR must not specify INTO");
if (forUpdate)
elog(ERROR, "DECLARE/UPDATE is not supported"
"\n\tCursors must be READ ONLY");
qry->into = makeNode(RangeVar);
qry->into->relname = portalname;
qry->isPortal = TRUE;
qry->isBinary = binary; /* internal portal */
}
else
{
/* SELECT */
qry->into = into;
qry->isPortal = FALSE;
qry->isBinary = FALSE;
}
/*
* Any column names from CREATE TABLE AS need to be attached to both
* the top level and the leftmost subquery. We do not do this earlier
* because we do *not* want the targetnames list to be affected.
*/
qry->into = into;
if (intoColNames)
{
applyColumnNames(qry->targetList, intoColNames);
@@ -1938,8 +1897,6 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt)
*/
if (stmt->into)
elog(ERROR, "INTO is only allowed on first SELECT of UNION/INTERSECT/EXCEPT");
if (stmt->portalname) /* should not happen */
elog(ERROR, "Portal may not appear in UNION/INTERSECT/EXCEPT");
/* We don't support forUpdate with set ops at the moment. */
if (stmt->forUpdate)
elog(ERROR, "SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT");
@@ -2327,6 +2284,27 @@ transformAlterTableStmt(ParseState *pstate, AlterTableStmt *stmt,
return qry;
}
static Query *
transformDeclareCursorStmt(ParseState *pstate, DeclareCursorStmt *stmt)
{
Query *result = makeNode(Query);
List *extras_before = NIL,
*extras_after = NIL;
result->commandType = CMD_UTILITY;
result->utilityStmt = (Node *) stmt;
stmt->query = (Node *) transformStmt(pstate, stmt->query,
&extras_before, &extras_after);
/* Shouldn't get any extras, since grammar only allows SelectStmt */
if (extras_before || extras_after)
elog(ERROR, "transformDeclareCursorStmt: internal error");
return result;
}
static Query *
transformPrepareStmt(ParseState *pstate, PrepareStmt *stmt)
{

127
src/backend/parser/gram.y
View File

@@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.404 2003/02/16 02:30:38 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.405 2003/03/10 03:53:50 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@@ -135,12 +135,12 @@ static void doNegateFloat(Value *v);
CreateDomainStmt CreateGroupStmt CreateOpClassStmt CreatePLangStmt
CreateSchemaStmt CreateSeqStmt CreateStmt
CreateAssertStmt CreateTrigStmt CreateUserStmt
CreatedbStmt CursorStmt DefineStmt DeleteStmt
CreatedbStmt DeclareCursorStmt DefineStmt DeleteStmt
DropGroupStmt DropOpClassStmt DropPLangStmt DropStmt
DropAssertStmt DropTrigStmt DropRuleStmt DropCastStmt
DropUserStmt DropdbStmt ExplainStmt FetchStmt
GrantStmt IndexStmt InsertStmt ListenStmt LoadStmt
LockStmt NotifyStmt OptimizableStmt
LockStmt NotifyStmt ExplainableStmt PreparableStmt
CreateFunctionStmt ReindexStmt RemoveAggrStmt
RemoveFuncStmt RemoveOperStmt RenameStmt RevokeStmt
RuleActionStmt RuleActionStmtOrEmpty RuleStmt
@@ -241,7 +241,7 @@ static void doNegateFloat(Value *v);
%type <ival> opt_interval
%type <node> overlay_placing substr_from substr_for
%type <boolean> opt_instead opt_cursor opt_analyze
%type <boolean> opt_instead opt_analyze
%type <boolean> index_opt_unique opt_verbose opt_full
%type <boolean> opt_freeze opt_default opt_recheck
%type <defelt> opt_binary opt_oids copy_delimiter
@@ -249,7 +249,7 @@ static void doNegateFloat(Value *v);
%type <boolean> copy_from
%type <ival> direction reindex_type drop_type
opt_column event comment_type
opt_column event comment_type cursor_options
%type <ival> fetch_how_many
@@ -481,68 +481,72 @@ stmt :
| AlterDomainStmt
| AlterGroupStmt
| AlterTableStmt
| AlterUserStmt
| AlterUserSetStmt
| AlterUserStmt
| AnalyzeStmt
| CheckPointStmt
| ClosePortalStmt
| ClusterStmt
| CommentStmt
| ConstraintsSetStmt
| CopyStmt
| CreateStmt
| CreateAsStmt
| CreateAssertStmt
| CreateCastStmt
| CreateConversionStmt
| CreateDomainStmt
| CreateFunctionStmt
| CreateSchemaStmt
| CreateGroupStmt
| CreateSeqStmt
| CreateOpClassStmt
| CreatePLangStmt
| CreateAssertStmt
| CreateSchemaStmt
| CreateSeqStmt
| CreateStmt
| CreateTrigStmt
| CreateUserStmt
| ClusterStmt
| CreatedbStmt
| DeallocateStmt
| DeclareCursorStmt
| DefineStmt
| DropStmt
| TruncateStmt
| CommentStmt
| DeleteStmt
| DropAssertStmt
| DropCastStmt
| DropGroupStmt
| DropOpClassStmt
| DropPLangStmt
| DropAssertStmt
| DropTrigStmt
| DropRuleStmt
| DropStmt
| DropTrigStmt
| DropUserStmt
| DropdbStmt
| ExecuteStmt
| ExplainStmt
| FetchStmt
| GrantStmt
| IndexStmt
| InsertStmt
| ListenStmt
| UnlistenStmt
| LoadStmt
| LockStmt
| NotifyStmt
| PrepareStmt
| ReindexStmt
| RemoveAggrStmt
| RemoveOperStmt
| RemoveFuncStmt
| RemoveOperStmt
| RenameStmt
| RevokeStmt
| OptimizableStmt
| RuleStmt
| SelectStmt
| TransactionStmt
| ViewStmt
| LoadStmt
| CreatedbStmt
| DropdbStmt
| TruncateStmt
| UnlistenStmt
| UpdateStmt
| VacuumStmt
| AnalyzeStmt
| VariableResetStmt
| VariableSetStmt
| VariableShowStmt
| VariableResetStmt
| ConstraintsSetStmt
| CheckPointStmt
| CreateConversionStmt
| ViewStmt
| /*EMPTY*/
{ $$ = (Node *)NULL; }
;
@@ -3961,16 +3965,7 @@ opt_name_list:
*
*****************************************************************************/
ExplainStmt:
EXPLAIN opt_analyze opt_verbose OptimizableStmt
{
ExplainStmt *n = makeNode(ExplainStmt);
n->analyze = $2;
n->verbose = $3;
n->query = (Query*)$4;
$$ = (Node *)n;
}
| EXPLAIN opt_analyze opt_verbose ExecuteStmt
ExplainStmt: EXPLAIN opt_analyze opt_verbose ExplainableStmt
{
ExplainStmt *n = makeNode(ExplainStmt);
n->analyze = $2;
@@ -3980,6 +3975,15 @@ ExplainStmt:
}
;
ExplainableStmt:
SelectStmt
| InsertStmt
| UpdateStmt
| DeleteStmt
| DeclareCursorStmt
| ExecuteStmt /* by default all are $$=$1 */
;
opt_analyze:
analyze_keyword { $$ = TRUE; }
| /* EMPTY */ { $$ = FALSE; }
@@ -3992,7 +3996,7 @@ opt_analyze:
*
*****************************************************************************/
PrepareStmt: PREPARE name prep_type_clause AS OptimizableStmt
PrepareStmt: PREPARE name prep_type_clause AS PreparableStmt
{
PrepareStmt *n = makeNode(PrepareStmt);
n->name = $2;
@@ -4011,6 +4015,13 @@ prep_type_list: Typename { $$ = makeList1($1); }
{ $$ = lappend($1, $3); }
;
PreparableStmt:
SelectStmt
| InsertStmt
| UpdateStmt
| DeleteStmt /* by default all are $$=$1 */
;
/*****************************************************************************
*
* QUERY:
@@ -4053,26 +4064,6 @@ DeallocateStmt: DEALLOCATE name
}
;
/*****************************************************************************
* *
* Optimizable Stmts: *
* *
* one of the five queries processed by the planner *
* *
* [ultimately] produces query-trees as specified *
* in the query-spec document in ~postgres/ref *
* *
*****************************************************************************/
OptimizableStmt:
SelectStmt
| CursorStmt
| UpdateStmt
| InsertStmt
| DeleteStmt /* by default all are $$=$1 */
;
/*****************************************************************************
*
* QUERY:
@@ -4213,20 +4204,20 @@ UpdateStmt: UPDATE relation_expr
* CURSOR STATEMENTS
*
*****************************************************************************/
CursorStmt: DECLARE name opt_cursor CURSOR FOR SelectStmt
DeclareCursorStmt: DECLARE name cursor_options CURSOR FOR SelectStmt
{
SelectStmt *n = (SelectStmt *)$6;
DeclareCursorStmt *n = makeNode(DeclareCursorStmt);
n->portalname = $2;
n->binary = $3;
$$ = $6;
n->options = $3;
n->query = $6;
$$ = (Node *)n;
}
;
opt_cursor: BINARY { $$ = TRUE; }
| INSENSITIVE { $$ = FALSE; }
| SCROLL { $$ = FALSE; }
| INSENSITIVE SCROLL { $$ = FALSE; }
| /*EMPTY*/ { $$ = FALSE; }
cursor_options: /*EMPTY*/ { $$ = 0; }
| cursor_options BINARY { $$ = $1 | CURSOR_OPT_BINARY; }
| cursor_options SCROLL { $$ = $1 | CURSOR_OPT_SCROLL; }
| cursor_options INSENSITIVE { $$ = $1 | CURSOR_OPT_INSENSITIVE; }
;
/*****************************************************************************

4
src/backend/parser/parse_clause.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.110 2003/02/16 02:30:38 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.111 2003/03/10 03:53:51 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -414,7 +414,7 @@ transformRangeSubselect(ParseState *pstate, RangeSubselect *r)
if (query->commandType != CMD_SELECT)
elog(ERROR, "Expected SELECT query from subselect in FROM");
if (query->resultRelation != 0 || query->into != NULL || query->isPortal)
if (query->resultRelation != 0 || query->into != NULL)
elog(ERROR, "Subselect in FROM may not have SELECT INTO");
/*

3
src/backend/parser/parse_type.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_type.c,v 1.53 2003/02/19 23:41:15 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/parse_type.c,v 1.54 2003/03/10 03:53:51 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -455,7 +455,6 @@ parseTypeString(const char *str, Oid *type_id, int32 *typmod)
stmt->groupClause != NIL ||
stmt->havingClause != NULL ||
stmt->sortClause != NIL ||
stmt->portalname != NULL ||
stmt->limitOffset != NULL ||
stmt->limitCount != NULL ||
stmt->forUpdate != NIL ||