diff options
Diffstat (limited to 'src/backend/access/heap/visibilitymap.c')
| -rw-r--r-- | src/backend/access/heap/visibilitymap.c | 34 |
1 files changed, 19 insertions, 15 deletions
diff --git a/src/backend/access/heap/visibilitymap.c b/src/backend/access/heap/visibilitymap.c index eaab4beccbc..05422f10799 100644 --- a/src/backend/access/heap/visibilitymap.c +++ b/src/backend/access/heap/visibilitymap.c @@ -33,7 +33,7 @@ * is set, we know the condition is true, but if a bit is not set, it might or * might not be true. * - * Clearing both visibility map bits is not separately WAL-logged. The callers + * Clearing visibility map bits is not separately WAL-logged. The callers * must make sure that whenever a bit is cleared, the bit is cleared on WAL * replay of the updating operation as well. * @@ -104,13 +104,16 @@ */ #define MAPSIZE (BLCKSZ - MAXALIGN(SizeOfPageHeaderData)) +/* Number of heap blocks we can represent in one byte */ +#define HEAPBLOCKS_PER_BYTE (BITS_PER_BYTE / BITS_PER_HEAPBLOCK) + /* Number of heap blocks we can represent in one visibility map page. */ #define HEAPBLOCKS_PER_PAGE (MAPSIZE * HEAPBLOCKS_PER_BYTE) /* Mapping from heap block number to the right bit in the visibility map */ #define HEAPBLK_TO_MAPBLOCK(x) ((x) / HEAPBLOCKS_PER_PAGE) #define HEAPBLK_TO_MAPBYTE(x) (((x) % HEAPBLOCKS_PER_PAGE) / HEAPBLOCKS_PER_BYTE) -#define HEAPBLK_TO_MAPBIT(x) (((x) % HEAPBLOCKS_PER_BYTE) * BITS_PER_HEAPBLOCK) +#define HEAPBLK_TO_OFFSET(x) (((x) % HEAPBLOCKS_PER_BYTE) * BITS_PER_HEAPBLOCK) /* tables for fast counting of set bits for visible and frozen */ static const uint8 number_of_ones_for_visible[256] = { @@ -156,7 +159,7 @@ static void vm_extend(Relation rel, BlockNumber nvmblocks); /* - * visibilitymap_clear - clear all bits in visibility map + * visibilitymap_clear - clear all bits for one page in visibility map * * You must pass a buffer containing the correct map page to this function. * Call visibilitymap_pin first to pin the right one. This function doesn't do @@ -167,8 +170,8 @@ visibilitymap_clear(Relation rel, BlockNumber heapBlk, Buffer buf) { BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); int mapByte = HEAPBLK_TO_MAPBYTE(heapBlk); - int mapBit = HEAPBLK_TO_MAPBIT(heapBlk); - uint8 mask = VISIBILITYMAP_VALID_BITS << mapBit; + int mapOffset = HEAPBLK_TO_OFFSET(heapBlk); + uint8 mask = VISIBILITYMAP_VALID_BITS << mapOffset; char *map; #ifdef TRACE_VISIBILITYMAP @@ -267,7 +270,7 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf, { BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); uint32 mapByte = HEAPBLK_TO_MAPBYTE(heapBlk); - uint8 mapBit = HEAPBLK_TO_MAPBIT(heapBlk); + uint8 mapOffset = HEAPBLK_TO_OFFSET(heapBlk); Page page; uint8 *map; @@ -291,11 +294,11 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf, map = (uint8 *)PageGetContents(page); LockBuffer(vmBuf, BUFFER_LOCK_EXCLUSIVE); - if (flags != (map[mapByte] >> mapBit & VISIBILITYMAP_VALID_BITS)) + if (flags != (map[mapByte] >> mapOffset & VISIBILITYMAP_VALID_BITS)) { START_CRIT_SECTION(); - map[mapByte] |= (flags << mapBit); + map[mapByte] |= (flags << mapOffset); MarkBufferDirty(vmBuf); if (RelationNeedsWAL(rel)) @@ -338,8 +341,7 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf, * earlier call to visibilitymap_pin or visibilitymap_get_status on the same * relation. On return, *buf is a valid buffer with the map page containing * the bit for heapBlk, or InvalidBuffer. The caller is responsible for - * releasing *buf after it's done testing and setting bits, and must pass flags - * for which it needs to check the value in visibility map. + * releasing *buf after it's done testing and setting bits. * * NOTE: This function is typically called without a lock on the heap page, * so somebody else could change the bit just after we look at it. In fact, @@ -353,8 +355,9 @@ visibilitymap_get_status(Relation rel, BlockNumber heapBlk, Buffer *buf) { BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk); uint32 mapByte = HEAPBLK_TO_MAPBYTE(heapBlk); - uint8 mapBit = HEAPBLK_TO_MAPBIT(heapBlk); + uint8 mapOffset = HEAPBLK_TO_OFFSET(heapBlk); char *map; + uint8 result; #ifdef TRACE_VISIBILITYMAP elog(DEBUG1, "vm_get_status %s %d", RelationGetRelationName(rel), heapBlk); @@ -384,7 +387,8 @@ visibilitymap_get_status(Relation rel, BlockNumber heapBlk, Buffer *buf) * here, but for performance reasons we make it the caller's job to worry * about that. */ - return ((map[mapByte] >> mapBit) & VISIBILITYMAP_VALID_BITS); + result = ((map[mapByte] >> mapOffset) & VISIBILITYMAP_VALID_BITS); + return result; } /* @@ -456,7 +460,7 @@ visibilitymap_truncate(Relation rel, BlockNumber nheapblocks) /* last remaining block, byte, and bit */ BlockNumber truncBlock = HEAPBLK_TO_MAPBLOCK(nheapblocks); uint32 truncByte = HEAPBLK_TO_MAPBYTE(nheapblocks); - uint8 truncBit = HEAPBLK_TO_MAPBIT(nheapblocks); + uint8 truncOffset = HEAPBLK_TO_OFFSET(nheapblocks); #ifdef TRACE_VISIBILITYMAP elog(DEBUG1, "vm_truncate %s %d", RelationGetRelationName(rel), nheapblocks); @@ -478,7 +482,7 @@ visibilitymap_truncate(Relation rel, BlockNumber nheapblocks) * because we don't get a chance to clear the bits if the heap is extended * again. */ - if (truncByte != 0 || truncBit != 0) + if (truncByte != 0 || truncOffset != 0) { Buffer mapBuffer; Page page; @@ -511,7 +515,7 @@ visibilitymap_truncate(Relation rel, BlockNumber nheapblocks) * ((1 << 7) - 1) = 01111111 *---- */ - map[truncByte] &= (1 << truncBit) - 1; + map[truncByte] &= (1 << truncOffset) - 1; MarkBufferDirty(mapBuffer); UnlockReleaseBuffer(mapBuffer); |