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Measure Bloom index signature-length reloption in bits, not words.

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Per discussion, this is a more understandable and future-proof way of
exposing the setting to users.  On-disk, we can still store it in words,
so as to not break on-disk compatibility with beta1.

Along the way, clean up the code associated with Bloom reloptions.
Provide explicit macros for default and maximum lengths rather than
having magic numbers buried in multiple places in the code.  Drop
the adjustBloomOptions() code altogether: it was useless in view of
the fact that reloptions.c already performed default-substitution and
range checking for the options.  Rename a couple of macros and types
for more clarity.

Discussion: <23767.1464926580@sss.pgh.pa.us>
This commit is contained in:
Tom Lane
2016-06-03 10:52:36 -04:00
parent fdfaccfa79
commit ee4af347ba
4 changed files with 86 additions and 93 deletions
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33
contrib/bloom/bloom.h
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@ -79,18 +79,31 @@ typedef BloomPageOpaqueData *BloomPageOpaque;
#define BLOOM_HEAD_BLKNO (1) /* first data page */
/*
* Maximum of bloom signature length in uint16. Actual value
* is 512 bytes
* We store Bloom signatures as arrays of uint16 words.
*/
#define MAX_BLOOM_LENGTH (256)
typedef uint16 BloomSignatureWord;
#define SIGNWORDBITS ((int) (BITS_PER_BYTE * sizeof(BloomSignatureWord)))
/*
* Default and maximum Bloom signature length in bits.
*/
#define DEFAULT_BLOOM_LENGTH (5 * SIGNWORDBITS)
#define MAX_BLOOM_LENGTH (256 * SIGNWORDBITS)
/*
* Default and maximum signature bits generated per index key.
*/
#define DEFAULT_BLOOM_BITS 2
#define MAX_BLOOM_BITS (MAX_BLOOM_LENGTH - 1)
/* Bloom index options */
typedef struct BloomOptions
{
int32 vl_len_; /* varlena header (do not touch directly!) */
int bloomLength; /* length of signature in uint16 */
int bitSize[INDEX_MAX_KEYS]; /* signature bits per index
* key */
int bloomLength; /* length of signature in words (not bits!) */
int bitSize[INDEX_MAX_KEYS]; /* # of bits generated for each
* index key */
} BloomOptions;
/*
@ -143,12 +156,10 @@ typedef struct BloomState
/*
* Tuples are very different from all other relations
*/
typedef uint16 SignType;
typedef struct BloomTuple
{
ItemPointerData heapPtr;
SignType sign[FLEXIBLE_ARRAY_MEMBER];
BloomSignatureWord sign[FLEXIBLE_ARRAY_MEMBER];
} BloomTuple;
#define BLOOMTUPLEHDRSZ offsetof(BloomTuple, sign)
@ -156,7 +167,7 @@ typedef struct BloomTuple
/* Opaque data structure for bloom index scan */
typedef struct BloomScanOpaqueData
{
SignType *sign; /* Scan signature */
BloomSignatureWord *sign; /* Scan signature */
BloomState state;
} BloomScanOpaqueData;
@ -170,7 +181,7 @@ extern void BloomFillMetapage(Relation index, Page metaPage);
extern void BloomInitMetapage(Relation index);
extern void BloomInitPage(Page page, uint16 flags);
extern Buffer BloomNewBuffer(Relation index);
extern void signValue(BloomState * state, SignType * sign, Datum value, int attno);
extern void signValue(BloomState * state, BloomSignatureWord * sign, Datum value, int attno);
extern BloomTuple *BloomFormTuple(BloomState * state, ItemPointer iptr, Datum *values, bool *isnull);
extern bool BloomPageAddItem(BloomState * state, Page page, BloomTuple * tuple);