Function ReadBuffer_common

src/backend/storage/buffer/bufmgr.c:894–1193

* ReadBuffer_common -- common logic for all ReadBuffer variants * * *hit is set to true if the request was satisfied from shared buffer cache. */

 * *hit is set to true if the request was satisfied from shared buffer cache.
 */
static Buffer
ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
				  BlockNumber blockNum, ReadBufferMode mode,
				  BufferAccessStrategy strategy, bool *hit)
{
	BufferDesc *bufHdr;
	Block		bufBlock;
	bool		found;
	bool		isExtend;

	if (ReadBuffer_hook)
	{
	    return ReadBuffer_hook(smgr, relpersistence, forkNum, blockNum, mode, strategy, hit);
	}

	/*
	 * Temp tables in Cloudberry use shared buffers so that backends executing
	 * multiple slices of the same query can share them.
	 */
	bool		isLocalBuf = false; /* SmgrIsTemp(smgr); */

	*hit = false;

	Assert(smgr != NULL);

	/* Make sure we will have room to remember the buffer pin */
	ResourceOwnerEnlargeBuffers(CurrentResourceOwner);

	isExtend = (blockNum == P_NEW);

	TRACE_POSTGRESQL_BUFFER_READ_START(forkNum, blockNum,
									   smgr->smgr_rnode.node.spcNode,
									   smgr->smgr_rnode.node.dbNode,
									   smgr->smgr_rnode.node.relNode,
									   smgr->smgr_rnode.backend,
									   isExtend);

	/* Substitute proper block number if caller asked for P_NEW */
	if (isExtend)
	{
		blockNum = smgrnblocks(smgr, forkNum);
		/* Fail if relation is already at maximum possible length */
		if (blockNum == P_NEW)
			ereport(ERROR,
					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
					 errmsg("cannot extend relation %s beyond %u blocks",
							relpath(smgr->smgr_rnode, forkNum),
							P_NEW)));
	}

	if (isLocalBuf)
	{
		bufHdr = LocalBufferAlloc(smgr, forkNum, blockNum, &found, InvalidBuffer);
		if (found)
			pgBufferUsage.local_blks_hit++;
		else if (isExtend)
			pgBufferUsage.local_blks_written++;
		else if (mode == RBM_NORMAL || mode == RBM_NORMAL_NO_LOG ||