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This clause changes the behavior of SELECT locking clauses in the presence of locked rows: instead of causing a process to block waiting for the locks held by other processes (or raise an error, with NOWAIT), SKIP LOCKED makes the new reader skip over such rows. While this is not appropriate behavior for general purposes, there are some cases in which it is useful, such as queue-like tables. Catalog version bumped because this patch changes the representation of stored rules. Reviewed by Craig Ringer (based on a previous attempt at an implementation by Simon Riggs, who also provided input on the syntax used in the current patch), David Rowley, and Álvaro Herrera. Author: Thomas Munro
45 lines
1.5 KiB
C
45 lines
1.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* analyze.h
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* parse analysis for optimizable statements
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*
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*
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* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/parser/analyze.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef ANALYZE_H
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#define ANALYZE_H
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#include "parser/parse_node.h"
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/* Hook for plugins to get control at end of parse analysis */
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typedef void (*post_parse_analyze_hook_type) (ParseState *pstate,
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Query *query);
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extern PGDLLIMPORT post_parse_analyze_hook_type post_parse_analyze_hook;
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extern Query *parse_analyze(Node *parseTree, const char *sourceText,
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Oid *paramTypes, int numParams);
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extern Query *parse_analyze_varparams(Node *parseTree, const char *sourceText,
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Oid **paramTypes, int *numParams);
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extern Query *parse_sub_analyze(Node *parseTree, ParseState *parentParseState,
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CommonTableExpr *parentCTE,
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bool locked_from_parent);
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extern Query *transformTopLevelStmt(ParseState *pstate, Node *parseTree);
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extern Query *transformStmt(ParseState *pstate, Node *parseTree);
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extern bool analyze_requires_snapshot(Node *parseTree);
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extern char *LCS_asString(LockClauseStrength strength);
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extern void CheckSelectLocking(Query *qry, LockClauseStrength strength);
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extern void applyLockingClause(Query *qry, Index rtindex,
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LockClauseStrength strength,
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LockWaitPolicy waitPolicy, bool pushedDown);
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#endif /* ANALYZE_H */
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