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Postgres FD Implementation
Commit 2584029e authored by Bruce Momjian's avatar Bruce Momjian
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Rename locking structure names to be clearer. Add narrative to 

backend flowchart.
parent f21fa6a7
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Showing with 324 additions and 311 deletions
src/backend/storage/lmgr/lock.c
View file @ 2584029e
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src/backend/storage/lmgr/multi.c
View file @ 2584029e
......@@ -12,7 +12,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/Attic/multi.c,v 1.18 1998/06/28 21:17:35 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/Attic/multi.c,v 1.19 1998/06/30 02:33:31 momjian Exp $
*
* NOTES:
* (1) The lock.c module assumes that the caller here is doing
......@@ -30,10 +30,10 @@
#include "miscadmin.h" /* MyDatabaseId */
static bool
MultiAcquire(LockTableId tableId, LOCKTAG *tag, LOCKTYPE locktype,
MultiAcquire(LOCKMETHOD lockmethod, LOCKTAG *tag, LOCKMODE lockmode,
PG_LOCK_LEVEL level);
static bool
MultiRelease(LockTableId tableId, LOCKTAG *tag, LOCKTYPE locktype,
MultiRelease(LOCKMETHOD lockmethod, LOCKTAG *tag, LOCKMODE lockmode,
PG_LOCK_LEVEL level);
/*
......@@ -78,25 +78,27 @@ static int MultiPrios[] = {
* Lock table identifier for this lock table. The multi-level
* lock table is ONE lock table, not three.
*/
LockTableId MultiTableId = (LockTableId) NULL;
LockTableId ShortTermTableId = (LockTableId) NULL;
LOCKMETHOD MultiTableId = (LOCKMETHOD) NULL;
#ifdef NOT_USED
LOCKMETHOD ShortTermTableId = (LOCKMETHOD) NULL;
#endif
/*
* Create the lock table described by MultiConflicts and Multiprio.
*/
LockTableId
LOCKMETHOD
InitMultiLevelLocks()
{
int tableId;
int lockmethod;
tableId = LockTableInit("LockTable", MultiConflicts, MultiPrios, 5);
MultiTableId = tableId;
lockmethod = LockMethodTableInit("MultiLevelLockTable", MultiConflicts, MultiPrios, 5);
MultiTableId = lockmethod;
if (!(MultiTableId))
elog(ERROR, "InitMultiLocks: couldnt initialize lock table");
/* -----------------------
* No short term lock table for now. -Jeff 15 July 1991
*
* ShortTermTableId = LockTableRename(tableId);
* ShortTermTableId = LockTableRename(lockmethod);
* if (! (ShortTermTableId)) {
* elog(ERROR,"InitMultiLocks: couldnt rename lock table");
* }
......@@ -111,7 +113,7 @@ InitMultiLevelLocks()
* Returns: TRUE if the lock can be set, FALSE otherwise.
*/
bool
MultiLockReln(LockInfo linfo, LOCKTYPE locktype)
MultiLockReln(LockInfo linfo, LOCKMODE lockmode)
{
LOCKTAG tag;
......@@ -122,7 +124,7 @@ MultiLockReln(LockInfo linfo, LOCKTYPE locktype)
MemSet(&tag, 0, sizeof(tag));
tag.relId = linfo->lRelId.relId;
tag.dbId = linfo->lRelId.dbId;
return (MultiAcquire(MultiTableId, &tag, locktype, RELN_LEVEL));
return (MultiAcquire(MultiTableId, &tag, lockmode, RELN_LEVEL));
}
/*
......@@ -134,7 +136,7 @@ MultiLockReln(LockInfo linfo, LOCKTYPE locktype)
* at the page and relation level.
*/
bool
MultiLockTuple(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype)
MultiLockTuple(LockInfo linfo, ItemPointer tidPtr, LOCKMODE lockmode)
{
LOCKTAG tag;
......@@ -149,14 +151,14 @@ MultiLockTuple(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype)
/* not locking any valid Tuple, just the page */
tag.tupleId = *tidPtr;
return (MultiAcquire(MultiTableId, &tag, locktype, TUPLE_LEVEL));
return (MultiAcquire(MultiTableId, &tag, lockmode, TUPLE_LEVEL));
}
/*
* same as above at page level
*/
bool
MultiLockPage(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype)
MultiLockPage(LockInfo linfo, ItemPointer tidPtr, LOCKMODE lockmode)
{
LOCKTAG tag;
......@@ -179,7 +181,7 @@ MultiLockPage(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype)
tag.relId = linfo->lRelId.relId;
tag.dbId = linfo->lRelId.dbId;
BlockIdCopy(&(tag.tupleId.ip_blkid), &(tidPtr->ip_blkid));
return (MultiAcquire(MultiTableId, &tag, locktype, PAGE_LEVEL));
return (MultiAcquire(MultiTableId, &tag, lockmode, PAGE_LEVEL));
}
/*
......@@ -189,12 +191,12 @@ MultiLockPage(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype)
* Side Effects:
*/
static bool
MultiAcquire(LockTableId tableId,
MultiAcquire(LOCKMETHOD lockmethod,
LOCKTAG *tag,
LOCKTYPE locktype,
LOCKMODE lockmode,
PG_LOCK_LEVEL level)
{
LOCKTYPE locks[N_LEVELS];
LOCKMODE locks[N_LEVELS];
int i,
status;
LOCKTAG xxTag,
......@@ -213,19 +215,19 @@ MultiAcquire(LockTableId tableId,
switch (level)
{
case RELN_LEVEL:
locks[0] = locktype;
locks[0] = lockmode;
locks[1] = NO_LOCK;
locks[2] = NO_LOCK;
break;
case PAGE_LEVEL:
locks[0] = locktype + INTENT;
locks[1] = locktype;
locks[0] = lockmode + INTENT;
locks[1] = lockmode;
locks[2] = NO_LOCK;
break;
case TUPLE_LEVEL:
locks[0] = locktype + INTENT;
locks[1] = locktype + INTENT;
locks[2] = locktype;
locks[0] = lockmode + INTENT;
locks[1] = lockmode + INTENT;
locks[2] = lockmode;
break;
default:
elog(ERROR, "MultiAcquire: bad lock level");
......@@ -274,7 +276,7 @@ MultiAcquire(LockTableId tableId,
break;
}
status = LockAcquire(tableId, tmpTag, locks[i]);
status = LockAcquire(lockmethod, tmpTag, locks[i]);
if (!status)
{
......@@ -285,7 +287,7 @@ MultiAcquire(LockTableId tableId,
* the last level lock we successfully acquired
*/
retStatus = FALSE;
MultiRelease(tableId, tag, locktype, i);
MultiRelease(lockmethod, tag, lockmode, i);
/* now leave the loop. Don't try for any more locks */
break;
}
......@@ -300,7 +302,7 @@ MultiAcquire(LockTableId tableId,
*/
#ifdef NOT_USED
bool
MultiReleasePage(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype)
MultiReleasePage(LockInfo linfo, ItemPointer tidPtr, LOCKMODE lockmode)
{
LOCKTAG tag;
......@@ -316,7 +318,7 @@ MultiReleasePage(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype)
tag.dbId = linfo->lRelId.dbId;
BlockIdCopy(&(tag.tupleId.ip_blkid), &(tidPtr->ip_blkid));
return (MultiRelease(MultiTableId, &tag, locktype, PAGE_LEVEL));
return (MultiRelease(MultiTableId, &tag, lockmode, PAGE_LEVEL));
}
#endif
......@@ -326,7 +328,7 @@ MultiReleasePage(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype)
* ------------------
*/
bool
MultiReleaseReln(LockInfo linfo, LOCKTYPE locktype)
MultiReleaseReln(LockInfo linfo, LOCKMODE lockmode)
{
LOCKTAG tag;
......@@ -340,7 +342,7 @@ MultiReleaseReln(LockInfo linfo, LOCKTYPE locktype)
tag.relId = linfo->lRelId.relId;
tag.dbId = linfo->lRelId.dbId;
return (MultiRelease(MultiTableId, &tag, locktype, RELN_LEVEL));
return (MultiRelease(MultiTableId, &tag, lockmode, RELN_LEVEL));
}
/*
......@@ -349,12 +351,12 @@ MultiReleaseReln(LockInfo linfo, LOCKTYPE locktype)
* Returns: TRUE if successful, FALSE otherwise.
*/
static bool
MultiRelease(LockTableId tableId,
MultiRelease(LOCKMETHOD lockmethod,
LOCKTAG *tag,
LOCKTYPE locktype,
LOCKMODE lockmode,
PG_LOCK_LEVEL level)
{
LOCKTYPE locks[N_LEVELS];
LOCKMODE locks[N_LEVELS];
int i,
status;
LOCKTAG xxTag,
......@@ -366,22 +368,22 @@ MultiRelease(LockTableId tableId,
switch (level)
{
case RELN_LEVEL:
locks[0] = locktype;
locks[0] = lockmode;
locks[1] = NO_LOCK;
locks[2] = NO_LOCK;
break;
case PAGE_LEVEL:
locks[0] = locktype + INTENT;
locks[1] = locktype;
locks[0] = lockmode + INTENT;
locks[1] = lockmode;
locks[2] = NO_LOCK;
break;
case TUPLE_LEVEL:
locks[0] = locktype + INTENT;
locks[1] = locktype + INTENT;
locks[2] = locktype;
locks[0] = lockmode + INTENT;
locks[1] = lockmode + INTENT;
locks[2] = lockmode;
break;
default:
elog(ERROR, "MultiRelease: bad locktype");
elog(ERROR, "MultiRelease: bad lockmode");
}
/*
......@@ -423,7 +425,7 @@ MultiRelease(LockTableId tableId,
ItemPointerCopy(&tmpTag->tupleId, &tag->tupleId);
break;
}
status = LockRelease(tableId, tmpTag, locks[i]);
status = LockRelease(lockmethod, tmpTag, locks[i]);
if (!status)
elog(ERROR, "MultiRelease: couldn't release after error");
}
......
src/backend/storage/lmgr/proc.c
View file @ 2584029e
......@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.38 1998/06/27 15:47:46 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.39 1998/06/30 02:33:32 momjian Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -46,7 +46,7 @@
* This is so that we can support more backends. (system-wide semaphore
* sets run out pretty fast.) -ay 4/95
*
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.38 1998/06/27 15:47:46 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.39 1998/06/30 02:33:32 momjian Exp $
*/
#include <sys/time.h>
#include <unistd.h>
......@@ -580,7 +580,7 @@ ProcWakeup(PROC *proc, int errType)
* released.
*/
int
ProcLockWakeup(PROC_QUEUE *queue, char *ltable, char *lock)
ProcLockWakeup(PROC_QUEUE *queue, LOCKMETHOD lockmethod, LOCK *lock)
{
PROC *proc;
int count;
......@@ -590,8 +590,8 @@ ProcLockWakeup(PROC_QUEUE *queue, char *ltable, char *lock)
proc = (PROC *) MAKE_PTR(queue->links.prev);
count = 0;
while ((LockResolveConflicts((LOCKTAB *) ltable,
(LOCK *) lock,
while ((LockResolveConflicts(lockmethod,
lock,
proc->token,
proc->xid) == STATUS_OK))
{
......@@ -602,7 +602,7 @@ ProcLockWakeup(PROC_QUEUE *queue, char *ltable, char *lock)
* between the time we release the lock master (spinlock) and the
* time that the awoken process begins executing again.
*/
GrantLock((LOCK *) lock, proc->token);
GrantLock(lock, proc->token);
queue->size--;
/*
......
src/backend/storage/lmgr/single.c
View file @ 2584029e
......@@ -13,7 +13,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/Attic/single.c,v 1.6 1998/06/28 21:17:35 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/Attic/single.c,v 1.7 1998/06/30 02:33:32 momjian Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -32,7 +32,7 @@
* Returns: TRUE if the lock can be set, FALSE otherwise.
*/
bool
SingleLockReln(LockInfo linfo, LOCKTYPE locktype, int action)
SingleLockReln(LockInfo linfo, LOCKMODE lockmode, int action)
{
LOCKTAG tag;
......@@ -47,9 +47,9 @@ SingleLockReln(LockInfo linfo, LOCKTYPE locktype, int action)
tag.tupleId.ip_posid = InvalidOffsetNumber;
if (action == UNLOCK)
return (LockRelease(MultiTableId, &tag, locktype));
return (LockRelease(MultiTableId, &tag, lockmode));
else
return (LockAcquire(MultiTableId, &tag, locktype));
return (LockAcquire(MultiTableId, &tag, lockmode));
}
/*
......@@ -63,7 +63,7 @@ SingleLockReln(LockInfo linfo, LOCKTYPE locktype, int action)
bool
SingleLockPage(LockInfo linfo,
ItemPointer tidPtr,
LOCKTYPE locktype,
LOCKMODE lockmode,
int action)
{
LOCKTAG tag;
......@@ -80,7 +80,7 @@ SingleLockPage(LockInfo linfo,
if (action == UNLOCK)
return (LockRelease(MultiTableId, &tag, locktype));
return (LockRelease(MultiTableId, &tag, lockmode));
else
return (LockAcquire(MultiTableId, &tag, locktype));
return (LockAcquire(MultiTableId, &tag, lockmode));
}
src/include/storage/lmgr.h
View file @ 2584029e
......@@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: lmgr.h,v 1.11 1998/06/28 21:17:35 momjian Exp $
* $Id: lmgr.h,v 1.12 1998/06/30 02:33:32 momjian Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -72,10 +72,10 @@ extern void RelationSetWIntentLock(Relation relation);
extern void RelationUnsetWIntentLock(Relation relation);
/* single.c */
extern bool SingleLockReln(LockInfo linfo, LOCKTYPE locktype, int action);
extern bool SingleLockReln(LockInfo linfo, LOCKMODE lockmode, int action);
extern bool
SingleLockPage(LockInfo linfo, ItemPointer tidPtr,
LOCKTYPE locktype, int action);
LOCKMODE lockmode, int action);
/* proc.c */
extern void InitProcGlobal(IPCKey key);
......
src/include/storage/lock.h
View file @ 2584029e
......@@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: lock.h,v 1.14 1998/06/28 21:17:35 momjian Exp $
* $Id: lock.h,v 1.15 1998/06/30 02:33:33 momjian Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -36,26 +36,25 @@ typedef int MASK;
#define NLOCKS_PER_XACT 40
#define NLOCKENTS NLOCKS_PER_XACT*NBACKENDS
typedef int LOCK_TYPE;
typedef int LOCKTYPE;
typedef int LockTableId;
typedef int LOCKMODE;
typedef int LOCKMETHOD;
/* MAX_LOCKTYPES cannot be larger than the bits in MASK */
#define MAX_LOCKTYPES 6
/* MAX_LOCKMODES cannot be larger than the bits in MASK */
#define MAX_LOCKMODES 6
/*
* MAX_TABLES corresponds to the number of spin locks allocated in
* MAX_LOCK_METHODS corresponds to the number of spin locks allocated in
* CreateSpinLocks() or the number of shared memory locations allocated
* for lock table spin locks in the case of machines with TAS instructions.
*/
#define MAX_TABLES 2
#define MAX_LOCK_METHODS 2
#define INVALID_TABLEID 0
/*typedef struct LOCK LOCK; */
typedef struct ltag
typedef struct LTAG
{
Oid relId;
Oid dbId;
......@@ -67,31 +66,31 @@ typedef struct ltag
/* This is the control structure for a lock table. It
* lives in shared memory:
*
* tableID -- the handle used by the lock table's clients to
* refer to the table.
* lockmethod -- the handle used by the lock table's clients to
* refer to the type of lock table being used.
*
* nLockTypes -- number of lock types (READ,WRITE,etc) that
* numLockModes -- number of lock types (READ,WRITE,etc) that
* are defined on this lock table
*
* conflictTab -- this is an array of bitmasks showing lock
* type conflicts. conflictTab[i] is a mask with the j-th bit
* turned on if lock types i and j conflict.
*
* prio -- each locktype has a priority, so, for example, waiting
* prio -- each lockmode has a priority, so, for example, waiting
* writers can be given priority over readers (to avoid
* starvation).
*
* masterlock -- synchronizes access to the table
*
*/
typedef struct lockctl
typedef struct LOCKMETHODCTL
{
LockTableId tableId;
int nLockTypes;
int conflictTab[MAX_LOCKTYPES];
int prio[MAX_LOCKTYPES];
LOCKMETHOD lockmethod;
int numLockModes;
int conflictTab[MAX_LOCKMODES];
int prio[MAX_LOCKMODES];
SPINLOCK masterLock;
} LOCKCTL;
} LOCKMETHODCTL;
/*
* lockHash -- hash table on lock Ids,
......@@ -99,12 +98,12 @@ typedef struct lockctl
* multiple processes are holding the lock
* ctl - control structure described above.
*/
typedef struct ltable
typedef struct LOCKMETHODTABLE
{
HTAB *lockHash;
HTAB *xidHash;
LOCKCTL *ctl;
} LOCKTAB;
LOCKMETHODCTL *ctl;
} LOCKMETHODTABLE;
/* -----------------------
* A transaction never conflicts with its own locks. Hence, if
......@@ -148,7 +147,7 @@ typedef struct XIDLookupEnt
XIDTAG tag;
/* data */
int holders[MAX_LOCKTYPES];
int holders[MAX_LOCKMODES];
int nHolding;
SHM_QUEUE queue;
} XIDLookupEnt;
......@@ -156,7 +155,7 @@ typedef struct XIDLookupEnt
#define XID_TAGSIZE (sizeof(XIDTAG))
/* originally in procq.h */
typedef struct procQueue
typedef struct PROC_QUEUE
{
SHM_QUEUE links;
int size;
......@@ -174,7 +173,7 @@ typedef struct procQueue
* lock.
* nHolding -- total locks of all types.
*/
typedef struct Lock
typedef struct LOCK
{
/* hash key */
LOCKTAG tag;
......@@ -182,18 +181,18 @@ typedef struct Lock
/* data */
int mask;
PROC_QUEUE waitProcs;
int holders[MAX_LOCKTYPES];
int holders[MAX_LOCKMODES];
int nHolding;
int activeHolders[MAX_LOCKTYPES];
int activeHolders[MAX_LOCKMODES];
int nActive;
} LOCK;
#define LockGetLock_nHolders(l) l->nHolders
#define LockDecrWaitHolders(lock, locktype) \
#define LockDecrWaitHolders(lock, lockmode) \
( \
lock->nHolding--, \
lock->holders[locktype]-- \
lock->holders[lockmode]-- \
)
#define LockLockTable() SpinAcquire(LockMgrLock);
......@@ -206,16 +205,16 @@ extern SPINLOCK LockMgrLock;
*/
extern void InitLocks(void);
extern void LockDisable(int status);
extern LockTableId
LockTableInit(char *tabName, MASK *conflictsP, int *prioP,
int ntypes);
extern bool LockAcquire(LockTableId tableId, LOCKTAG *lockName, LOCKTYPE locktype);
extern LOCKMETHOD
LockMethodTableInit(char *tabName, MASK *conflictsP, int *prioP,
int numModes);
extern bool LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode);
extern int
LockResolveConflicts(LOCKTAB *ltable, LOCK *lock, LOCKTYPE locktype,
LockResolveConflicts(LOCKMETHOD lockmethod, LOCK *lock, LOCKMODE lockmode,
TransactionId xid);
extern bool LockRelease(LockTableId tableId, LOCKTAG *lockName, LOCKTYPE locktype);
extern void GrantLock(LOCK *lock, LOCKTYPE locktype);
extern bool LockReleaseAll(LockTableId tableId, SHM_QUEUE *lockQueue);
extern bool LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode);
extern void GrantLock(LOCK *lock, LOCKMODE lockmode);
extern bool LockReleaseAll(LOCKMETHOD lockmethod, SHM_QUEUE *lockQueue);
extern int LockShmemSize(void);
extern bool LockingDisabled(void);
extern bool DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check);
......
src/include/storage/multilev.h
View file @ 2584029e
......@@ -7,7 +7,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: multilev.h,v 1.9 1998/06/28 21:17:36 momjian Exp $
* $Id: multilev.h,v 1.10 1998/06/30 02:33:33 momjian Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -43,16 +43,18 @@ typedef int PG_LOCK_LEVEL;
/* multi.c */
extern LockTableId MultiTableId;
extern LockTableId ShortTermTableId;
extern LOCKMETHOD MultiTableId;
#ifdef NOT_USED
extern LOCKMETHOD ShortTermTableId;
#endif
/*
* function prototypes
*/
extern LockTableId InitMultiLevelLocks(void);
extern bool MultiLockReln(LockInfo linfo, LOCKTYPE locktype);
extern bool MultiLockTuple(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype);
extern bool MultiLockPage(LockInfo linfo, ItemPointer tidPtr, LOCKTYPE locktype);
extern bool MultiReleaseReln(LockInfo linfo, LOCKTYPE locktype);
extern LOCKMETHOD InitMultiLevelLocks(void);
extern bool MultiLockReln(LockInfo linfo, LOCKMODE lockmode);
extern bool MultiLockTuple(LockInfo linfo, ItemPointer tidPtr, LOCKMODE lockmode);
extern bool MultiLockPage(LockInfo linfo, ItemPointer tidPtr, LOCKMODE lockmode);
extern bool MultiReleaseReln(LockInfo linfo, LOCKMODE lockmode);
#endif /* MULTILEV_H */
src/include/storage/proc.h
View file @ 2584029e
......@@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: proc.h,v 1.11 1998/02/26 04:43:31 momjian Exp $
* $Id: proc.h,v 1.12 1998/06/30 02:33:33 momjian Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -100,7 +100,7 @@ extern void ProcQueueInit(PROC_QUEUE *queue);
extern int
ProcSleep(PROC_QUEUE *queue, SPINLOCK spinlock, int token,
int prio, LOCK *lock);
extern int ProcLockWakeup(PROC_QUEUE *queue, char *ltable, char *lock);
extern int ProcLockWakeup(PROC_QUEUE *queue, LOCKMETHOD lockmethod, LOCK *lock);
extern void ProcAddLock(SHM_QUEUE *elem);
extern void ProcReleaseSpins(PROC *proc);
extern void ProcFreeAllSemaphores(void);
......
src/tools/backend/index.html
View file @ 2584029e
......@@ -25,13 +25,13 @@ structure, like
The query is then identified as a <I>Utility</I> function or a more
complex query. A <I>Utility</I> query is processed by a
query-specific function in <A HREF="../../backend/commands">
commands.</A> A complex query, like <B>SELECT, UPDATE,</B> and
<B>DELETE</B> requires much more handling.
commands.</A> A complex query, like <CODE>SELECT, UPDATE,</CODE> and
<CODE>DELETE</CODE> requires much more handling.
<P>
The parser takes a complex query, and creates a
<A HREF="../../include/nodes/parsenodes.h">Query</A> structure that
contains all the elements used by complex queries. Query.qual holds the
<B>WHERE</B> clause qualification, which is filled in by
<CODE>WHERE</CODE> clause qualification, which is filled in by
<A HREF="../../backend/parser/parse_clause.c">transformWhereClause().</A>
Each table referenced in the query is represented by a <A
HREF="../../include/nodes/parsenodes.h"> RangeTableEntry,</A> and they
......@@ -39,19 +39,19 @@ are linked together to form the <I>range table</I> of the query, which is
generated by <A HREF="../../backend/parser/parse_clause.c">
makeRangeTable().</A> Query.rtable holds the queries range table.
<P>
Certain queries, like <B>SELECT,</B> return columns of data. Other
queries, like <B>INSERT</B> and <B>UPDATE,</B> specify the columns
Certain queries, like <CODE>SELECT,</CODE> return columns of data. Other
queries, like <CODE>INSERT</CODE> and <CODE>UPDATE,</CODE> specify the columns
modified by the query. These column references are converted to <A
HREF="../../include/nodes/primnodes.h">Resdom</A> entries, which are
linked together to make up the <I>target list</I> of the query. The
target list is stored in Query.targetList, which is generated by
<A HREF="../../backend/parser/parse_target.c">transformTargetList().</A>
<P>
Other query elements, like aggregates(<B>SUM()</B>), <B>GROUP BY,</B>
<B>ORDER BY</B> are also stored in their own Query fields.
Other query elements, like aggregates(<CODE>SUM()</CODE>), <CODE>GROUP BY,</CODE>
<CODE>ORDER BY</CODE> are also stored in their own Query fields.
<P>
The next step is for the Query to be modified by any <B>VIEWS</B> or
<B>RULES</B> that may apply to the query. This is performed by the <A
The next step is for the Query to be modified by any <CODE>VIEWS</CODE> or
<CODE>RULES</CODE> that may apply to the query. This is performed by the <A
HREF="../../backend/rewrite">rewrite</A> system.
<P>
The <A HREF="../../backend/optimizer">optimizer</A> takes the Query
......@@ -60,7 +60,7 @@ HREF="../..//include/nodes/plannodes.h">Plan,</A> which contains the
operations to be performed to execute the query. The <A
HREF="../../backend/optimizer/path">path</A> module determines the best
table join order and join type of each table in the RangeTable, using
Query.qual(<B>WHERE</B> clause) to consider optimal index usage.
Query.qual(<CODE>WHERE</CODE> clause) to consider optimal index usage.
<P>
The Plan is then passed to the <A
HREF="../../backend/executor">executor</A> for execution, and the result
......@@ -81,15 +81,25 @@ data/index buffer cache block
<LI>Shared Buf Lookup Table - lookup of buffer cache block address using
table name and block number(<A HREF="../../include/storage/buf_internals.h">
BufferTag</A>)
<LI><A HREF="../../include/storage/lock.h">LockTable (ctl)</A> - lock table
structure, specifiying table, lock types, and backends holding or
waiting on lock
<LI>LockTable (lock hash) - lookup of LockTable structures using relation,
database object ids
<LI>LockTable (xid hash) - lookup of LockTable structures using
transaction id, LockTable address
<LI>MultiLevelLockTable (ctl) - <A
HREF="../../include/storage/lock.h">LOCKCTL</A> control structure for
each locking method. Currently, only multi-level locking is used.
<LI>MultiLevelLockTable (lock hash) - the <A
HREF="../../include/storage/lock.h">LOCK</A> structure, looked up using
relation, database object ids(<A
HREF="../../include/storage/lock.h">LOCKTAG)</A>. The lock table structure contains the
lock modes(read, write) and circular linked list of backends (<A
HREF="../../include/storage/proc.h">PROC</A> structure pointers) waiting
on the lock.
<LI>MultiLevelLockTable (xid hash) - lookup of LOCK structure address
using transaction id, LOCK address. It is used to quickly check if the
current transaction already has any locks on a table, rather than having
to search through all the held locks. It also stores the modes
(read/write) of the locks held by the current transaction. The returned
<A HREF="../../include/storage/lock.h">XIDLookupEnt</A> structure also
contains a pointer to the backend's PROC.lockQueue.
<LI><A HREF="../../include/storage/proc.h">Proc Header</A> - information
about each backend, including locks held/waiting, indexed by process id
about each backend, including locks held/waiting, indexed by process id
</UL>
Each data structure is created by calling <A
HREF="../../backend/storage/ipc/shmem.c">ShmemInitStruct(),</A> and
......
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