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8f9f198603
as per recent discussions. Invent SubTransactionIds that are managed like CommandIds (ie, counter is reset at start of each top transaction), and use these instead of TransactionIds to keep track of subtransaction status in those modules that need it. This means that a subtransaction does not need an XID unless it actually inserts/modifies rows in the database. Accordingly, don't assign it an XID nor take a lock on the XID until it tries to do that. This saves a lot of overhead for subtransactions that are only used for error recovery (eg plpgsql exceptions). Also, arrange to release a subtransaction's XID lock as soon as the subtransaction exits, in both the commit and abort cases. This avoids holding many unique locks after a long series of subtransactions. The price is some additional overhead in XactLockTableWait, but that seems acceptable. Finally, restructure the state machine in xact.c to have a more orthogonal set of states for subtransactions.
252 lines
7.2 KiB
C
252 lines
7.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* rel.h
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* POSTGRES relation descriptor (a/k/a relcache entry) definitions.
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*
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*
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* Portions Copyright (c) 1996-2004, 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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* $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.80 2004/09/16 16:58:43 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef REL_H
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#define REL_H
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#include "access/tupdesc.h"
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#include "catalog/pg_am.h"
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#include "catalog/pg_class.h"
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#include "catalog/pg_index.h"
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#include "rewrite/prs2lock.h"
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#include "storage/block.h"
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#include "storage/relfilenode.h"
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/*
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* LockRelId and LockInfo really belong to lmgr.h, but it's more convenient
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* to declare them here so we can have a LockInfoData field in a Relation.
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*/
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typedef struct LockRelId
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{
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Oid relId; /* a relation identifier */
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Oid dbId; /* a database identifier */
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} LockRelId;
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typedef struct LockInfoData
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{
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LockRelId lockRelId;
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} LockInfoData;
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typedef LockInfoData *LockInfo;
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/*
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* Likewise, this struct really belongs to trigger.h, but for convenience
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* we put it here.
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*/
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typedef struct Trigger
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{
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Oid tgoid; /* OID of trigger (pg_trigger row) */
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/* Remaining fields are copied from pg_trigger, see pg_trigger.h */
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char *tgname;
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Oid tgfoid;
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int16 tgtype;
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bool tgenabled;
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bool tgisconstraint;
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Oid tgconstrrelid;
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bool tgdeferrable;
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bool tginitdeferred;
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int16 tgnargs;
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int16 tgattr[FUNC_MAX_ARGS];
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char **tgargs;
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} Trigger;
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typedef struct TriggerDesc
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{
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/*
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* Index data to identify which triggers are which. Since each
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* trigger can appear in more than one class, for each class we
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* provide a list of integer indexes into the triggers array.
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*/
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#define TRIGGER_NUM_EVENT_CLASSES 3
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uint16 n_before_statement[TRIGGER_NUM_EVENT_CLASSES];
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uint16 n_before_row[TRIGGER_NUM_EVENT_CLASSES];
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uint16 n_after_row[TRIGGER_NUM_EVENT_CLASSES];
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uint16 n_after_statement[TRIGGER_NUM_EVENT_CLASSES];
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int *tg_before_statement[TRIGGER_NUM_EVENT_CLASSES];
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int *tg_before_row[TRIGGER_NUM_EVENT_CLASSES];
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int *tg_after_row[TRIGGER_NUM_EVENT_CLASSES];
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int *tg_after_statement[TRIGGER_NUM_EVENT_CLASSES];
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/* The actual array of triggers is here */
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Trigger *triggers;
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int numtriggers;
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} TriggerDesc;
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/*
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* Same for the statistics collector data in Relation and scan data.
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*/
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typedef struct PgStat_Info
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{
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void *tabentry;
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bool no_stats;
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bool heap_scan_counted;
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bool index_scan_counted;
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} PgStat_Info;
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/*
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* Here are the contents of a relation cache entry.
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*/
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typedef struct RelationData
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{
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RelFileNode rd_node; /* relation physical identifier */
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/* use "struct" here to avoid needing to include smgr.h: */
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struct SMgrRelationData *rd_smgr; /* cached file handle, or NULL */
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BlockNumber rd_targblock; /* current insertion target block, or
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* InvalidBlockNumber */
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int rd_refcnt; /* reference count */
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bool rd_istemp; /* rel uses the local buffer mgr */
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bool rd_isnailed; /* rel is nailed in cache */
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bool rd_isvalid; /* relcache entry is valid */
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char rd_indexvalid; /* state of rd_indexlist: 0 = not valid, 1
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* = valid, 2 = temporarily forced */
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SubTransactionId rd_createSubid; /* rel was created in current xact */
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/*
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* rd_createSubid is the ID of the highest subtransaction the rel has
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* survived into; or zero if the rel was not created in the current
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* top transaction. This should be relied on only for optimization
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* purposes; it is possible for new-ness to be "forgotten" (eg, after
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* CLUSTER).
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*/
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Form_pg_class rd_rel; /* RELATION tuple */
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TupleDesc rd_att; /* tuple descriptor */
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Oid rd_id; /* relation's object id */
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List *rd_indexlist; /* list of OIDs of indexes on relation */
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LockInfoData rd_lockInfo; /* lock mgr's info for locking relation */
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RuleLock *rd_rules; /* rewrite rules */
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MemoryContext rd_rulescxt; /* private memory cxt for rd_rules, if any */
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TriggerDesc *trigdesc; /* Trigger info, or NULL if rel has none */
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/* These are non-NULL only for an index relation: */
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Form_pg_index rd_index; /* pg_index tuple describing this index */
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struct HeapTupleData *rd_indextuple; /* all of pg_index tuple */
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/* "struct HeapTupleData *" avoids need to include htup.h here */
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Form_pg_am rd_am; /* pg_am tuple for index's AM */
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/*
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* index access support info (used only for an index relation)
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*
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* Note: only default operators and support procs for each opclass are
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* cached, namely those with subtype zero. The arrays are indexed by
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* strategy or support number, which is a sufficient identifier given
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* that restriction.
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*/
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MemoryContext rd_indexcxt; /* private memory cxt for this stuff */
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Oid *rd_operator; /* OIDs of index operators */
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RegProcedure *rd_support; /* OIDs of support procedures */
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struct FmgrInfo *rd_supportinfo; /* lookup info for support
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* procedures */
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/* "struct FmgrInfo" avoids need to include fmgr.h here */
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List *rd_indexprs; /* index expression trees, if any */
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List *rd_indpred; /* index predicate tree, if any */
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/* statistics collection area */
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PgStat_Info pgstat_info;
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} RelationData;
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typedef RelationData *Relation;
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/* ----------------
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* RelationPtr is used in the executor to support index scans
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* where we have to keep track of several index relations in an
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* array. -cim 9/10/89
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* ----------------
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*/
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typedef Relation *RelationPtr;
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/*
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* RelationIsValid
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* True iff relation descriptor is valid.
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*/
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#define RelationIsValid(relation) PointerIsValid(relation)
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#define InvalidRelation ((Relation) NULL)
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/*
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* RelationHasReferenceCountZero
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* True iff relation reference count is zero.
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*
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* Note:
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* Assumes relation descriptor is valid.
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*/
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#define RelationHasReferenceCountZero(relation) \
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((bool)((relation)->rd_refcnt == 0))
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/*
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* RelationGetForm
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* Returns pg_class tuple for a relation.
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*
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* Note:
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* Assumes relation descriptor is valid.
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*/
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#define RelationGetForm(relation) ((relation)->rd_rel)
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/*
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* RelationGetRelid
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* Returns the OID of the relation
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*/
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#define RelationGetRelid(relation) ((relation)->rd_id)
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/*
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* RelationGetNumberOfAttributes
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* Returns the number of attributes in a relation.
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*/
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#define RelationGetNumberOfAttributes(relation) ((relation)->rd_rel->relnatts)
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/*
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* RelationGetDescr
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* Returns tuple descriptor for a relation.
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*/
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#define RelationGetDescr(relation) ((relation)->rd_att)
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/*
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* RelationGetRelationName
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* Returns the rel's name.
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*
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* Note that the name is only unique within the containing namespace.
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*/
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#define RelationGetRelationName(relation) \
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(NameStr((relation)->rd_rel->relname))
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/*
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* RelationGetNamespace
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* Returns the rel's namespace OID.
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*/
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#define RelationGetNamespace(relation) \
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((relation)->rd_rel->relnamespace)
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/*
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* RELATION_IS_LOCAL
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* If a rel is either temp or newly created in the current transaction,
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* it can be assumed to be visible only to the current backend.
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*
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* Beware of multiple eval of argument
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*/
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#define RELATION_IS_LOCAL(relation) \
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((relation)->rd_istemp || \
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(relation)->rd_createSubid != InvalidSubTransactionId)
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/* routines in utils/cache/relcache.c */
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extern void RelationIncrementReferenceCount(Relation rel);
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extern void RelationDecrementReferenceCount(Relation rel);
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#endif /* REL_H */
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