Add safety check on expression nesting depth. Default value is set by
a config.h #define, and the runtime value can be controlled via SET.
This commit is contained in:
Tom Lane
parent
341b328b18
commit
0e314d747e
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@ -1,5 +1,5 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/set.sgml,v 1.31 2000/02/27 21:07:03 tgl Exp $
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/set.sgml,v 1.32 2000/03/17 05:29:03 tgl Exp $
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Postgres documentation
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-->
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@ -770,6 +770,30 @@ SET TRANSACTION ISOLATION LEVEL { READ COMMITTED | SERIALIZABLE }
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>MAX_EXPR_DEPTH</term>
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<listitem>
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<para>
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Sets the maximum expression nesting depth that the parser will
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accept. The default value is high enough for any normal query,
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but you can raise it if you need to. (But if you raise it too high,
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you run the risk of backend crashes due to stack overflow.)
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<variablelist>
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<varlistentry>
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<term><replaceable class="parameter">integer</replaceable></term>
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<term>ON</term>
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<listitem>
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<para>
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Maximum depth.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect2>
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@ -9,7 +9,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/commands/variable.c,v 1.31 2000/02/27 21:10:41 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/commands/variable.c,v 1.32 2000/03/17 05:29:04 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -25,6 +25,7 @@
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#include "miscadmin.h"
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#include "optimizer/cost.h"
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#include "optimizer/paths.h"
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#include "parser/parse_expr.h"
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#include "utils/builtins.h"
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#include "utils/tqual.h"
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#include "utils/trace.h"
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@ -86,6 +87,9 @@ static bool parse_geqo(char *);
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static bool show_ksqo(void);
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static bool reset_ksqo(void);
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static bool parse_ksqo(char *);
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static bool reset_max_expr_depth(void);
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static bool show_max_expr_depth(void);
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static bool parse_max_expr_depth(char *);
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static bool show_XactIsoLevel(void);
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static bool reset_XactIsoLevel(void);
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static bool parse_XactIsoLevel(char *);
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@ -935,6 +939,44 @@ reset_ksqo()
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return TRUE;
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}
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/*
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* MAX_EXPR_DEPTH
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*/
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static bool
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parse_max_expr_depth(char *value)
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{
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int newval;
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if (value == NULL)
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{
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reset_max_expr_depth();
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return TRUE;
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}
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newval = pg_atoi(value, sizeof(int), '\0');
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if (newval < 10) /* somewhat arbitrary limit */
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elog(ERROR, "Bad value for MAX_EXPR_DEPTH (%s)", value);
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max_expr_depth = newval;
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return TRUE;
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}
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static bool
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show_max_expr_depth()
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{
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elog(NOTICE, "MAX_EXPR_DEPTH is %d", max_expr_depth);
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return TRUE;
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}
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static bool
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reset_max_expr_depth(void)
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{
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max_expr_depth = DEFAULT_MAX_EXPR_DEPTH;
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return TRUE;
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}
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/* SET TRANSACTION */
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static bool
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@ -1103,6 +1145,10 @@ static struct VariableParsers
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{
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"ksqo", parse_ksqo, show_ksqo, reset_ksqo
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},
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{
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"max_expr_depth", parse_max_expr_depth,
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show_max_expr_depth, reset_max_expr_depth
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},
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{
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"XactIsoLevel", parse_XactIsoLevel, show_XactIsoLevel, reset_XactIsoLevel
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},
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.73 2000/03/14 23:06:32 thomas Exp $
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* $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.74 2000/03/17 05:29:05 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -32,6 +32,11 @@
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#include "utils/builtins.h"
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#include "utils/syscache.h"
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int max_expr_depth = DEFAULT_MAX_EXPR_DEPTH;
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static int expr_depth_counter = 0;
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static Node *parser_typecast_constant(Value *expr, TypeName *typename);
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static Node *parser_typecast_expression(ParseState *pstate,
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Node *expr, TypeName *typename);
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@ -40,6 +45,20 @@ static Node *transformIdent(ParseState *pstate, Ident *ident, int precedence);
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static Node *transformIndirection(ParseState *pstate, Node *basenode,
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List *indirection);
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/*
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* Initialize for parsing a new query.
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*
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* We reset the expression depth counter here, in case it was left nonzero
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* due to elog()'ing out of the last parsing operation.
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*/
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void
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parse_expr_init(void)
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{
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expr_depth_counter = 0;
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}
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/*
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* transformExpr -
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* analyze and transform expressions. Type checking and type casting is
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@ -55,6 +74,17 @@ transformExpr(ParseState *pstate, Node *expr, int precedence)
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if (expr == NULL)
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return NULL;
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/*
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* Guard against an overly complex expression leading to coredump
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* due to stack overflow here, or in later recursive routines that
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* traverse expression trees. Note that this is very unlikely to
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* happen except with pathological queries; but we don't want someone
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* to be able to crash the backend quite that easily...
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*/
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if (++expr_depth_counter > max_expr_depth)
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elog(ERROR, "Expression too complex: nesting depth exceeds max_expr_depth = %d",
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max_expr_depth);
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switch (nodeTag(expr))
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{
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case T_Attr:
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@ -532,6 +562,8 @@ transformExpr(ParseState *pstate, Node *expr, int precedence)
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break;
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}
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expr_depth_counter--;
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return result;
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}
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@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/parser/parser.c,v 1.43 2000/01/26 05:56:43 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/parser/parser.c,v 1.44 2000/03/17 05:29:05 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -16,6 +16,7 @@
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#include "parser/analyze.h"
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#include "parser/gramparse.h"
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#include "parser/parser.h"
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#include "parser/parse_expr.h"
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#if defined(FLEX_SCANNER)
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extern void DeleteBuffer(void);
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@ -46,6 +47,8 @@ parser(char *str, Oid *typev, int nargs)
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parsetree = NIL; /* in case parser forgets to set it */
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parser_init(typev, nargs);
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parse_expr_init();
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yyresult = yyparse();
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#if defined(FLEX_SCANNER)
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@ -3,7 +3,7 @@
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*
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* Copyright 2000 by PostgreSQL Global Development Group
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*
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* $Header: /cvsroot/pgsql/src/bin/psql/tab-complete.c,v 1.15 2000/03/05 13:30:19 petere Exp $
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* $Header: /cvsroot/pgsql/src/bin/psql/tab-complete.c,v 1.16 2000/03/17 05:29:06 tgl Exp $
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*/
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/*-----------
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@ -195,6 +195,7 @@ char ** psql_completion(char *text, int start, int end)
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"client_encoding",
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"server_encoding",
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"KSQO",
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"max_expr_depth",
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"XactIsoLevel",
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"PG_Options",
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NULL
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@ -1,8 +1,14 @@
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/* the purpose of this file is to reduce the use of #ifdef's through
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* the code base by those porting the software, and to facilitate the
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* eventual use of autoconf to build the server
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/*
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* PostgreSQL configuration-settings file.
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*
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* config.h.in is processed by configure to produce config.h.
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*
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* If you want to modify any of the tweakable settings in the first part
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* of this file, you can do it in config.h.in before running configure,
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* or in config.h afterwards. Of course, if you edit config.h, then your
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* changes will be overwritten the next time you run configure.
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*
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* $Id: config.h.in,v 1.110 2000/03/17 05:29:06 tgl Exp $
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*/
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#ifndef CONFIG_H
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@ -11,7 +17,7 @@
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/*
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* Default runtime limit on number of backend server processes per postmaster;
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* this is just the default setting for the postmaster's -N switch.
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* (Actual value is set by configure script.)
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* (Actual value is now set by configure script.)
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*/
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#undef DEF_MAXBACKENDS
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@ -70,17 +76,11 @@
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/*
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* DEF_PGPORT is the TCP port number on which the Postmaster listens by
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* default. This can be overriden by command options, environment variables,
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* and the postconfig hook. (set by configure script)
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* and the postconfig hook. (now set by configure script)
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*/
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#undef DEF_PGPORT
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/*
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* If you do not plan to use Host based authentication,
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* comment out the following line (set by build script)
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*/
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#undef HBA
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/*
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* As soon as the backend blocks on a lock, it waits this number of seconds
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* before checking for a deadlock.
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@ -89,12 +89,6 @@
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*/
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#define DEADLOCK_CHECK_TIMER 1
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/*
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* This flag enables the use of indexes in plans generated for function
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* executions which normally are always executed with sequential scans.
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*/
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#define INDEXSCAN_PATCH
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/*
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* Maximum number of columns in an index and maximum number of arguments
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* to a function. They must be the same value.
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@ -121,16 +115,6 @@
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*/
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/* #define UNSAFE_FLOATS */
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/*
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* There is a bug in the function executor. The backend crashes while trying to
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* execute an sql function containing an utility command (create, notify, ...).
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* The bug is part in the planner, which returns a number of plans different
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* than the number of commands if there are utility commands in the query, and
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* in part in the function executor which assumes that all commands are normal
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* query commands and causes a SIGSEGV trying to execute commands without plan.
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*/
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#define FUNC_UTIL_PATCH
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/*
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* Define this to make libpgtcl's "pg_result -assign" command process C-style
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* backslash sequences in returned tuple data and convert Postgres array
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@ -188,7 +172,7 @@
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#define FASTBUILD /* access/nbtree/nbtsort.c */
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/*
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* TBL_FREE_CMD_MEMORY: free memory allocated for an user query inside
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* TBL_FREE_CMD_MEMORY: free memory allocated for a user query inside
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* transaction block after this query is done.
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*/
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#define TBL_FREE_CMD_MEMORY
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@ -232,9 +216,22 @@
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*/
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#define MAXPGPATH 1024
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/*
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* DEFAULT_MAX_EXPR_DEPTH: default value of max_expr_depth SET variable.
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*/
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#define DEFAULT_MAX_EXPR_DEPTH 10000
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/*
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* Leftover cruft for enabling long-since-verified patches.
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* You don't want to touch these.
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*/
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#define INDEXSCAN_PATCH
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#define FUNC_UTIL_PATCH
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/*
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*------------------------------------------------------------------------
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* The following is set using configure.
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* Everything past here is set by the configure script.
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*------------------------------------------------------------------------
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*/
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: parse_expr.h,v 1.17 2000/02/26 21:11:09 tgl Exp $
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* $Id: parse_expr.h,v 1.18 2000/03/17 05:29:07 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -20,9 +20,12 @@
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#define EXPR_COLUMN_FIRST 1
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#define EXPR_RELATION_FIRST 2
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extern int max_expr_depth;
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extern Node *transformExpr(ParseState *pstate, Node *expr, int precedence);
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extern Oid exprType(Node *expr);
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extern int32 exprTypmod(Node *expr);
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extern bool exprIsLengthCoercion(Node *expr, int32 *coercedTypmod);
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extern void parse_expr_init(void);
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#endif /* PARSE_EXPR_H */
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