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User-defined switch point between sparse-dense HLL encodings.

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antirez
2014-04-15 17:46:51 +02:00
parent d541f65d66
commit 402110f9fd
5 changed files with 32 additions and 6 deletions
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11
src/hyperloglog.c
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@ -176,7 +176,7 @@
* involved in updating the sparse representation is not justified by the
* memory savings. The exact maximum length of the sparse representation
* when this implementation switches to the dense representation is
* configured via the define HLL_SPARSE_MAX.
* configured via the define server.hll_sparse_max_bytes.
*/
struct hllhdr {
@ -202,8 +202,6 @@ struct hllhdr {
#define HLL_SPARSE 1 /* Sparse encoding */
#define HLL_MAX_ENCODING 1
#define HLL_SPARSE_MAX 3000
static char *invalid_hll_err = "Corrupted HLL object detected";
/* =========================== Low level bit macros ========================= */
@ -634,7 +632,7 @@ int hllSparseToDense(robj *o) {
* As a side effect the function may promote the HLL representation from
* sparse to dense: this happens when a register requires to be set to a value
* not representable with the sparse representation, or when the resulting
* size would be greater than HLL_SPARSE_MAX. */
* size would be greater than server.hll_sparse_max_bytes. */
int hllSparseAdd(robj *o, unsigned char *ele, size_t elesize) {
struct hllhdr *hdr;
uint8_t oldcount, count, *sparse, *end, *p, *prev, *next;
@ -815,7 +813,8 @@ int hllSparseAdd(robj *o, unsigned char *ele, size_t elesize) {
int oldlen = is_xzero ? 2 : 1;
int deltalen = seqlen-oldlen;
if (deltalen > 0 && sdslen(o->ptr)+deltalen > HLL_SPARSE_MAX) goto promote;
if (deltalen > 0 &&
sdslen(o->ptr)+deltalen > server.hll_sparse_max_bytes) goto promote;
if (deltalen && next) memmove(next+deltalen,next,end-next);
sdsIncrLen(o->ptr,deltalen);
memcpy(p,seq,seqlen);
@ -1312,7 +1311,7 @@ void pfselftestCommand(redisClient *c) {
/* Make sure that for small cardinalities we use sparse
* encoding. */
if (j == checkpoint && j < HLL_SPARSE_MAX/2) {
if (j == checkpoint && j < server.hll_sparse_max_bytes/2) {
hdr2 = o->ptr;
if (hdr2->encoding != HLL_SPARSE) {
addReplyError(c, "TESTFAILED sparse encoding not used");