Revert "Avoid creation of the free space map for small heap relations."

This reverts commit ac88d2962a96a9c7e83d5acfc28fe49a72812086.

1 files changed, 6 insertions, 269 deletions

diff --git a/src/backend/storage/freespace/freespace.c b/src/backend/storage/freespace/freespace.c
index 5f46391b681..eee82860575 100644
--- a/src/backend/storage/freespace/freespace.c
+++ b/src/backend/storage/freespace/freespace.c
@@ -76,14 +76,6 @@
 #define FSM_ROOT_LEVEL	(FSM_TREE_DEPTH - 1)
 #define FSM_BOTTOM_LEVEL 0
 
-/* Status codes for the local map. */
-
-/* Either already tried, or beyond the end of the relation */
-#define FSM_LOCAL_NOT_AVAIL 0x00
-
-/* Available to try */
-#define FSM_LOCAL_AVAIL		0x01
-
 /*
  * The internal FSM routines work on a logical addressing scheme. Each
  * level of the tree can be thought of as a separately addressable file.
@@ -97,17 +89,6 @@ typedef struct
 /* Address of the root page. */
 static const FSMAddress FSM_ROOT_ADDRESS = {FSM_ROOT_LEVEL, 0};
 
-/* Local map of block numbers for small heaps with no FSM. */
-typedef struct
-{
-	BlockNumber nblocks;
-	uint8		map[HEAP_FSM_CREATION_THRESHOLD];
-} FSMLocalMap;
-
-static FSMLocalMap fsm_local_map = {0, {FSM_LOCAL_NOT_AVAIL}};
-
-#define FSM_LOCAL_MAP_EXISTS (fsm_local_map.nblocks > 0)
-
 /* functions to navigate the tree */
 static FSMAddress fsm_get_child(FSMAddress parent, uint16 slot);
 static FSMAddress fsm_get_parent(FSMAddress child, uint16 *slot);
@@ -126,14 +107,10 @@ static Size fsm_space_cat_to_avail(uint8 cat);
 /* workhorse functions for various operations */
 static int fsm_set_and_search(Relation rel, FSMAddress addr, uint16 slot,
 				   uint8 newValue, uint8 minValue);
-static void fsm_local_set(Relation rel, BlockNumber cur_nblocks);
 static BlockNumber fsm_search(Relation rel, uint8 min_cat);
-static BlockNumber fsm_local_search(void);
 static uint8 fsm_vacuum_page(Relation rel, FSMAddress addr,
 				BlockNumber start, BlockNumber end,
 				bool *eof);
-static bool fsm_allow_writes(Relation rel, BlockNumber heapblk,
-				BlockNumber nblocks, BlockNumber *get_nblocks);
 
 
 /******** Public API ********/
@@ -150,46 +127,13 @@ static bool fsm_allow_writes(Relation rel, BlockNumber heapblk,
  * amount of free space available on that page and then try again (see
  * RecordAndGetPageWithFreeSpace).  If InvalidBlockNumber is returned,
  * extend the relation.
- *
- * For very small heap relations that don't have a FSM, we try every other
- * page before extending the relation.  To keep track of which pages have
- * been tried, initialize a local in-memory map of pages.
  */
 BlockNumber
-GetPageWithFreeSpace(Relation rel, Size spaceNeeded, bool check_fsm_only)
+GetPageWithFreeSpace(Relation rel, Size spaceNeeded)
 {
 	uint8		min_cat = fsm_space_needed_to_cat(spaceNeeded);
-	BlockNumber target_block,
-				nblocks;
-
-	/* First try the FSM, if it exists. */
-	target_block = fsm_search(rel, min_cat);
-
-	if (target_block == InvalidBlockNumber &&
-		(rel->rd_rel->relkind == RELKIND_RELATION ||
-		 rel->rd_rel->relkind == RELKIND_TOASTVALUE) &&
-		!check_fsm_only)
-	{
-		nblocks = RelationGetNumberOfBlocks(rel);
-
-		if (nblocks > HEAP_FSM_CREATION_THRESHOLD)
-		{
-			/*
-			 * If the FSM knows nothing of the rel, try the last page before
-			 * we give up and extend.  This avoids one-tuple-per-page syndrome
-			 * during bootstrapping or in a recently-started system.
-			 */
-			target_block = nblocks - 1;
-		}
-		else if (nblocks > 0)
-		{
-			/* Create or update local map and get first candidate block. */
-			fsm_local_set(rel, nblocks);
-			target_block = fsm_local_search();
-		}
-	}
 
-	return target_block;
+	return fsm_search(rel, min_cat);
 }
 
 /*
@@ -200,47 +144,16 @@ GetPageWithFreeSpace(Relation rel, Size spaceNeeded, bool check_fsm_only)
  * also some effort to return a page close to the old page; if there's a
  * page with enough free space on the same FSM page where the old one page
  * is located, it is preferred.
- *
- * For very small heap relations that don't have a FSM, we update the local
- * map to indicate we have tried a page, and return the next page to try.
  */
 BlockNumber
 RecordAndGetPageWithFreeSpace(Relation rel, BlockNumber oldPage,
 							  Size oldSpaceAvail, Size spaceNeeded)
 {
-	int			old_cat;
-	int			search_cat;
+	int			old_cat = fsm_space_avail_to_cat(oldSpaceAvail);
+	int			search_cat = fsm_space_needed_to_cat(spaceNeeded);
 	FSMAddress	addr;
 	uint16		slot;
 	int			search_slot;
-	BlockNumber nblocks = InvalidBlockNumber;
-
-	/* First try the local map, if it exists. */
-	if (FSM_LOCAL_MAP_EXISTS)
-	{
-		Assert((rel->rd_rel->relkind == RELKIND_RELATION ||
-				rel->rd_rel->relkind == RELKIND_TOASTVALUE) &&
-			   fsm_local_map.map[oldPage] == FSM_LOCAL_AVAIL);
-
-		fsm_local_map.map[oldPage] = FSM_LOCAL_NOT_AVAIL;
-		return fsm_local_search();
-	}
-
-	if (!fsm_allow_writes(rel, oldPage, InvalidBlockNumber, &nblocks))
-	{
-		/*
-		 * If we have neither a local map nor a FSM, we probably just
-		 * tried the target block in the smgr relation entry and failed,
-		 * so we'll need to create the local map.
-		 */
-		fsm_local_set(rel, nblocks);
-		return fsm_local_search();
-	}
-
-	/* Normal FSM logic follows */
-
-	old_cat = fsm_space_avail_to_cat(oldSpaceAvail);
-	search_cat = fsm_space_needed_to_cat(spaceNeeded);
 
 	/* Get the location of the FSM byte representing the heap block */
 	addr = fsm_get_location(oldPage, &slot);
@@ -263,42 +176,21 @@ RecordAndGetPageWithFreeSpace(Relation rel, BlockNumber oldPage,
  * Note that if the new spaceAvail value is higher than the old value stored
  * in the FSM, the space might not become visible to searchers until the next
  * FreeSpaceMapVacuum call, which updates the upper level pages.
- *
- * Callers have no need for a local map.
  */
 void
-RecordPageWithFreeSpace(Relation rel, BlockNumber heapBlk,
-						Size spaceAvail, BlockNumber nblocks)
+RecordPageWithFreeSpace(Relation rel, BlockNumber heapBlk, Size spaceAvail)
 {
-	int			new_cat;
+	int			new_cat = fsm_space_avail_to_cat(spaceAvail);
 	FSMAddress	addr;
 	uint16		slot;
-	BlockNumber dummy;
-
-	if (!fsm_allow_writes(rel, heapBlk, nblocks, &dummy))
-		/* No FSM to update and no local map either */
-		return;
 
 	/* Get the location of the FSM byte representing the heap block */
 	addr = fsm_get_location(heapBlk, &slot);
 
-	new_cat = fsm_space_avail_to_cat(spaceAvail);
 	fsm_set_and_search(rel, addr, slot, new_cat, 0);
 }
 
 /*
- * Clear the local map.  We must call this when we have found a block with
- * enough free space, when we extend the relation, or on transaction abort.
- */
-void
-FSMClearLocalMap(void)
-{
-	fsm_local_map.nblocks = 0;
-	memset(&fsm_local_map.map, FSM_LOCAL_NOT_AVAIL,
-		   sizeof(fsm_local_map.map));
-}
-
-/*
  * XLogRecordPageWithFreeSpace - like RecordPageWithFreeSpace, for use in
  *		WAL replay
  */
@@ -312,30 +204,6 @@ XLogRecordPageWithFreeSpace(RelFileNode rnode, BlockNumber heapBlk,
 	BlockNumber blkno;
 	Buffer		buf;
 	Page		page;
-	bool		write_to_fsm;
-
-	/* This is meant to mirror the logic in fsm_allow_writes() */
-	if (heapBlk >= HEAP_FSM_CREATION_THRESHOLD)
-		write_to_fsm = true;
-	else
-	{
-		/* Open the relation at smgr level */
-		SMgrRelation smgr = smgropen(rnode, InvalidBackendId);
-
-		if (smgrexists(smgr, FSM_FORKNUM))
-			write_to_fsm = true;
-		else
-		{
-			BlockNumber heap_nblocks = smgrnblocks(smgr, MAIN_FORKNUM);
-			if (heap_nblocks > HEAP_FSM_CREATION_THRESHOLD)
-				write_to_fsm = true;
-			else
-				write_to_fsm = false;
-		}
-	}
-
-	if (!write_to_fsm)
-		return;
 
 	/* Get the location of the FSM byte representing the heap block */
 	addr = fsm_get_location(heapBlk, &slot);
@@ -1036,134 +904,3 @@ fsm_vacuum_page(Relation rel, FSMAddress addr,
 
 	return max_avail;
 }
-
-/*
- * For heaps, we prevent creation of the FSM unless the number of pages
- * exceeds HEAP_FSM_CREATION_THRESHOLD.  For tables that don't already have
- * a FSM, this will save an inode and a few kB of space.
- *
- * XXX The API is a little awkward -- if the caller passes a valid nblocks
- * value, it can avoid invoking a system call.  If the caller passes
- * InvalidBlockNumber and receives a false return value, it can get an
- * up-to-date relation size from get_nblocks.  This saves a few cycles in
- * the caller, which would otherwise need to get the relation size by itself.
- */
-static bool
-fsm_allow_writes(Relation rel, BlockNumber heapblk,
-				 BlockNumber nblocks, BlockNumber *get_nblocks)
-{
-	bool		skip_get_nblocks;
-
-	if (heapblk >= HEAP_FSM_CREATION_THRESHOLD)
-		return true;
-
-	/* Non-heap rels can always create a FSM. */
-	if (rel->rd_rel->relkind != RELKIND_RELATION &&
-		rel->rd_rel->relkind != RELKIND_TOASTVALUE)
-		return true;
-
-	/*
-	 * If the caller knows nblocks, we can avoid a system call later.
-	 * If it doesn't, maybe we have relpages from a previous VACUUM.
-	 * Since the table may have extended since then, we still have to
-	 * count the pages later if we can't return now.
-	 */
-	if (nblocks != InvalidBlockNumber)
-	{
-		if (nblocks > HEAP_FSM_CREATION_THRESHOLD)
-			return true;
-		else
-			skip_get_nblocks = true;
-	}
-	else
-	{
-		if (rel->rd_rel->relpages != InvalidBlockNumber &&
-			rel->rd_rel->relpages > HEAP_FSM_CREATION_THRESHOLD)
-			return true;
-		else
-			skip_get_nblocks = false;
-	}
-
-	RelationOpenSmgr(rel);
-	if (smgrexists(rel->rd_smgr, FSM_FORKNUM))
-		return true;
-
-	if (skip_get_nblocks)
-		return false;
-
-	/* last resort */
-	*get_nblocks = RelationGetNumberOfBlocks(rel);
-	if (*get_nblocks > HEAP_FSM_CREATION_THRESHOLD)
-		return true;
-	else
-		return false;
-}
-
-/*
- * Initialize or update the local map of blocks to try, for when there is
- * no FSM.
- *
- * When we initialize the map, the whole heap is potentially available to
- * try.  Testing revealed that trying every block can cause a small
- * performance dip compared to when we use a FSM, so we try every other
- * block instead.
- */
-static void
-fsm_local_set(Relation rel, BlockNumber cur_nblocks)
-{
-	BlockNumber blkno,
-				cached_target_block;
-
-	/* The local map must not be set already. */
-	Assert(!FSM_LOCAL_MAP_EXISTS);
-
-	/*
-	 * Starting at the current last block in the relation and working
-	 * backwards, mark alternating blocks as available.
-	 */
-	blkno = cur_nblocks - 1;
-	while (true)
-	{
-		fsm_local_map.map[blkno] = FSM_LOCAL_AVAIL;
-		if (blkno >= 2)
-			blkno -= 2;
-		else
-			break;
-	}
-
-	/* Cache the number of blocks. */
-	fsm_local_map.nblocks = cur_nblocks;
-
-	/* Set the status of the cached target block to 'unavailable'. */
-	cached_target_block = RelationGetTargetBlock(rel);
-	if (cached_target_block != InvalidBlockNumber &&
-		cached_target_block < cur_nblocks)
-		fsm_local_map.map[cached_target_block] = FSM_LOCAL_NOT_AVAIL;
-}
-
-/*
- * Search the local map for an available block to try, in descending order.
- * As such, there is no heuristic available to decide which order will be
- * better to try, but the probability of having space in the last block in the
- * map is higher because that is the most recent block added to the heap.
- *
- * This function is used when there is no FSM.
- */
-static BlockNumber
-fsm_local_search(void)
-{
-	BlockNumber		target_block;
-
-	/* Local map must be set by now. */
-	Assert(FSM_LOCAL_MAP_EXISTS);
-
-	target_block = fsm_local_map.nblocks;
-	do
-	{
-		target_block--;
-		if (fsm_local_map.map[target_block] == FSM_LOCAL_AVAIL)
-			return target_block;
-	} while (target_block > 0);
-
-	return InvalidBlockNumber;
-}