mirror of https://github.com/postgres/postgres
Vadim B. Mikheev
25 years ago
parent
2f4c9d39fe
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/*-------------------------------------------------------------------------
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* |
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* localbuf.c |
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* local buffer manager. Fast buffer manager for temporary tables |
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* or special cases when the operation is not visible to other backends. |
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* |
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* When a relation is being created, the descriptor will have rd_islocal |
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* set to indicate that the local buffer manager should be used. During |
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* the same transaction the relation is being created, any inserts or |
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* selects from the newly created relation will use the local buffer |
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* pool. rd_islocal is reset at the end of a transaction (commit/abort). |
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* This is useful for queries like SELECT INTO TABLE and create index. |
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* |
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc |
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* Portions Copyright (c) 1994-5, Regents of the University of California |
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* |
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* |
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* IDENTIFICATION |
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* $Header: /cvsroot/pgsql/src/backend/storage/buffer/Attic/xlog_localbuf.c,v 1.1 2000/10/28 16:20:56 vadim Exp $ |
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* |
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*------------------------------------------------------------------------- |
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*/ |
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#include <sys/types.h> |
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#include <sys/file.h> |
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#include <math.h> |
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#include <signal.h> |
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#include "postgres.h" |
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#include "executor/execdebug.h" |
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#include "storage/smgr.h" |
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#include "utils/relcache.h" |
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extern long int LocalBufferFlushCount; |
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int NLocBuffer = 64; |
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BufferDesc *LocalBufferDescriptors = NULL; |
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long *LocalRefCount = NULL; |
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static int nextFreeLocalBuf = 0; |
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/*#define LBDEBUG*/ |
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/*
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* LocalBufferAlloc - |
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* allocate a local buffer. We do round robin allocation for now. |
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*/ |
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BufferDesc * |
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LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr) |
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{ |
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int i; |
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BufferDesc *bufHdr = (BufferDesc *) NULL; |
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if (blockNum == P_NEW) |
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{ |
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blockNum = reln->rd_nblocks; |
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reln->rd_nblocks++; |
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} |
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/* a low tech search for now -- not optimized for scans */ |
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for (i = 0; i < NLocBuffer; i++) |
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{ |
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if (LocalBufferDescriptors[i].tag.rnode.relNode ==
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reln->rd_node.relNode && |
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LocalBufferDescriptors[i].tag.blockNum == blockNum) |
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{ |
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#ifdef LBDEBUG |
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fprintf(stderr, "LB ALLOC (%u,%d) %d\n", |
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RelationGetRelid(reln), blockNum, -i - 1); |
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#endif |
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LocalRefCount[i]++; |
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*foundPtr = TRUE; |
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return &LocalBufferDescriptors[i]; |
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} |
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} |
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#ifdef LBDEBUG |
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fprintf(stderr, "LB ALLOC (%u,%d) %d\n", |
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RelationGetRelid(reln), blockNum, -nextFreeLocalBuf - 1); |
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#endif |
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/* need to get a new buffer (round robin for now) */ |
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for (i = 0; i < NLocBuffer; i++) |
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{ |
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int b = (nextFreeLocalBuf + i) % NLocBuffer; |
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if (LocalRefCount[b] == 0) |
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{ |
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bufHdr = &LocalBufferDescriptors[b]; |
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LocalRefCount[b]++; |
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nextFreeLocalBuf = (b + 1) % NLocBuffer; |
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break; |
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} |
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} |
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if (bufHdr == NULL) |
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elog(ERROR, "no empty local buffer."); |
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/*
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* this buffer is not referenced but it might still be dirty (the last |
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* transaction to touch it doesn't need its contents but has not |
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* flushed it). if that's the case, write it out before reusing it! |
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*/ |
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if (bufHdr->flags & BM_DIRTY || bufHdr->cntxDirty) |
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{ |
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Relation bufrel = RelationNodeCacheGetRelation(bufHdr->tag.rnode); |
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Assert(bufrel != NULL); |
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/* flush this page */ |
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smgrwrite(DEFAULT_SMGR, bufrel, bufHdr->tag.blockNum, |
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(char *) MAKE_PTR(bufHdr->data)); |
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LocalBufferFlushCount++; |
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/*
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* drop relcache refcount incremented by |
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* RelationIdCacheGetRelation |
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*/ |
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RelationDecrementReferenceCount(bufrel); |
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} |
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/*
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* it's all ours now. |
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* |
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* We need not in tblNode currently but will in future I think, |
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* when we'll give up rel->rd_fd to fmgr cache. |
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*/ |
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bufHdr->tag.rnode = reln->rd_node; |
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bufHdr->tag.blockNum = blockNum; |
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bufHdr->flags &= ~BM_DIRTY; |
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bufHdr->cntxDirty = false; |
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/*
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* lazy memory allocation. (see MAKE_PTR for why we need to do |
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* MAKE_OFFSET.) |
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*/ |
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if (bufHdr->data == (SHMEM_OFFSET) 0) |
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{ |
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char *data = (char *) malloc(BLCKSZ); |
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bufHdr->data = MAKE_OFFSET(data); |
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} |
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*foundPtr = FALSE; |
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return bufHdr; |
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} |
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/*
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* WriteLocalBuffer - |
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* writes out a local buffer |
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*/ |
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int |
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WriteLocalBuffer(Buffer buffer, bool release) |
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{ |
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int bufid; |
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Assert(BufferIsLocal(buffer)); |
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#ifdef LBDEBUG |
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fprintf(stderr, "LB WRITE %d\n", buffer); |
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#endif |
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bufid = -(buffer + 1); |
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LocalBufferDescriptors[bufid].flags |= BM_DIRTY; |
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if (release) |
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{ |
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Assert(LocalRefCount[bufid] > 0); |
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LocalRefCount[bufid]--; |
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} |
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return true; |
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} |
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/*
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* InitLocalBuffer - |
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* init the local buffer cache. Since most queries (esp. multi-user ones) |
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* don't involve local buffers, we delay allocating memory for actual the |
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* buffer until we need it. |
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*/ |
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void |
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InitLocalBuffer(void) |
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{ |
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int i; |
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/*
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* these aren't going away. I'm not gonna use palloc. |
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*/ |
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LocalBufferDescriptors = |
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(BufferDesc *) malloc(sizeof(BufferDesc) * NLocBuffer); |
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MemSet(LocalBufferDescriptors, 0, sizeof(BufferDesc) * NLocBuffer); |
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nextFreeLocalBuf = 0; |
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for (i = 0; i < NLocBuffer; i++) |
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{ |
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BufferDesc *buf = &LocalBufferDescriptors[i]; |
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/*
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* negative to indicate local buffer. This is tricky: shared |
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* buffers start with 0. We have to start with -2. (Note that the |
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* routine BufferDescriptorGetBuffer adds 1 to buf_id so our first |
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* buffer id is -1.) |
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*/ |
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buf->buf_id = -i - 2; |
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} |
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LocalRefCount = (long *) malloc(sizeof(long) * NLocBuffer); |
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MemSet(LocalRefCount, 0, sizeof(long) * NLocBuffer); |
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} |
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/*
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* LocalBufferSync |
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* |
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* Flush all dirty buffers in the local buffer cache at commit time. |
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* Since the buffer cache is only used for keeping relations visible |
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* during a transaction, we will not need these buffers again. |
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* |
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* Note that we have to *flush* local buffers because of them are not |
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* visible to checkpoint makers. But we can skip XLOG flush check. |
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*/ |
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void |
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LocalBufferSync(void) |
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{ |
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int i; |
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for (i = 0; i < NLocBuffer; i++) |
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{ |
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BufferDesc *buf = &LocalBufferDescriptors[i]; |
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Relation bufrel; |
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if (buf->flags & BM_DIRTY || buf->cntxDirty) |
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{ |
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#ifdef LBDEBUG |
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fprintf(stderr, "LB SYNC %d\n", -i - 1); |
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#endif |
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bufrel = RelationNodeCacheGetRelation(buf->tag.rnode); |
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Assert(bufrel != NULL); |
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smgrwrite(DEFAULT_SMGR, bufrel, buf->tag.blockNum, |
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(char *) MAKE_PTR(buf->data)); |
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smgrmarkdirty(DEFAULT_SMGR, bufrel, buf->tag.blockNum); |
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LocalBufferFlushCount++; |
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/* drop relcache refcount from RelationIdCacheGetRelation */ |
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RelationDecrementReferenceCount(bufrel); |
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buf->flags &= ~BM_DIRTY; |
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buf->cntxDirty = false; |
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} |
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} |
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MemSet(LocalRefCount, 0, sizeof(long) * NLocBuffer); |
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nextFreeLocalBuf = 0; |
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} |
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void |
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ResetLocalBufferPool(void) |
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{ |
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int i; |
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for (i = 0; i < NLocBuffer; i++) |
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{ |
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BufferDesc *buf = &LocalBufferDescriptors[i]; |
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buf->tag.rnode.relNode = InvalidOid; |
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buf->flags &= ~BM_DIRTY; |
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buf->cntxDirty = false; |
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buf->buf_id = -i - 2; |
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} |
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MemSet(LocalRefCount, 0, sizeof(long) * NLocBuffer); |
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nextFreeLocalBuf = 0; |
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} |
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@ -0,0 +1,24 @@ |
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/*
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* |
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* xlogdefs.h |
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* |
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* Postgres transaction log manager record pointer and |
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* system stratup number definitions |
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* |
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*/ |
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#ifndef XLOG_DEFS_H |
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#define XLOG_DEFS_H |
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typedef struct XLogRecPtr |
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{ |
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uint32 xlogid; /* log file #, 0 based */ |
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uint32 xrecoff; /* offset of record in log file */ |
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} XLogRecPtr; |
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/*
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* StartUpID (SUI) - system startups counter. It's to allow removing |
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* pg_log after shutdown, in future. |
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*/ |
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typedef uint32 StartUpID; |
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#endif /* XLOG_DEFS_H */ |
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