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Correct the HyperLogLog stale cache flag to prevent unnecessary computations.

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Set the MSB as documented.
This commit is contained in:
Mike Trinkala 2014-05-18 07:26:26 -07:00
parent 67133d2f48
commit ba52cd06c8
1 changed files with 4 additions and 4 deletions
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8
src/hyperloglog.c
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@ -188,8 +188,8 @@ struct hllhdr {
};
/* The cached cardinality MSB is used to signal validity of the cached value. */
#define HLL_INVALIDATE_CACHE(hdr) (hdr)->card[0] |= (1<<7)
#define HLL_VALID_CACHE(hdr) (((hdr)->card[0] & (1<<7)) == 0)
#define HLL_INVALIDATE_CACHE(hdr) (hdr)->card[7] |= (1<<7)
#define HLL_VALID_CACHE(hdr) (((hdr)->card[7] & (1<<7)) == 0)
#define HLL_P 14 /* The greater is P, the smaller the error. */
#define HLL_REGISTERS (1<<HLL_P) /* With P=14, 16384 registers. */
@ -953,7 +953,7 @@ double hllRawSum(uint8_t *registers, double *PE, int *ezp) {
return E;
}
/* Return the approximated cardinality of the set based on the armonic
/* Return the approximated cardinality of the set based on the harmonic
* mean of the registers values. 'hdr' points to the start of the SDS
* representing the String object holding the HLL representation.
*
@ -1385,7 +1385,7 @@ void pfselftestCommand(redisClient *c) {
/* Test 2: approximation error.
* The test adds unique elements and check that the estimated value
* is always reasonable bounds.
*
*
* We check that the error is smaller than 4 times than the expected
* standard error, to make it very unlikely for the test to fail because
* of a "bad" run.