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small refactor for readability

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This commit is contained in:
James Cor
2023-03-08 14:28:48 -08:00
parent 396c569486
commit 74e4a5c2e5
1 changed files with 19 additions and 11 deletions
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30
go/libraries/doltcore/sqle/index/z_encoding.go
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@@ -220,7 +220,15 @@ func zRangeSize(zRange ZRange, shamt int) (uint64, int) {
const cutThresh = 0.02
const depthThresh = 4
// shouldCut checks if the size of the removed ZRange divided by the size of the whole ZRange is smaller than cutThresh, stop
// Masks for every other bit to avoid un-interleaving
// Depending on prefixLength these will be shifted to either fill x or y values with 0s or 1s
// while not altering the bits of their counterparts
const xMask = 0x5555555555555555
const yMask = 0xAAAAAAAAAAAAAAAA
// shouldCut checks if the size of the removed ZRange divided by the size of the whole ZRange is smaller than cutThresh
// This is used to get splitZRanges to stop recursing
func shouldCut(cutRange ZRange, size float64, shamt int) bool {
cut, _ := zRangeSize(cutRange, shamt)
return (float64(cut) / size) >= cutThresh
@@ -249,15 +257,15 @@ func splitZRanges(zRange ZRange, zSize float64, zShamt, depth int, acc []ZRange)
// upper bound for left range; set 0 fill with 1s
suffixLength := 64 - prefixLength
zRangeL[1][0] |= 0xAAAAAAAAAAAAAAAA >> prefixLength // set suffix to all 1s
zRangeL[1][0] &= ^(1 << (suffixLength - 1)) // set first suffix bit to 0
zRangeL[1][1] |= 0xAAAAAAAAAAAAAAAA >> (prefixLength % 2) // set suffix to all 1s
zRangeL[1][0] |= yMask >> prefixLength // set suffix to all 1s
zRangeL[1][0] &= ^(1 << (suffixLength - 1)) // set first suffix bit to 0
zRangeL[1][1] |= yMask >> (prefixLength % 2) // set suffix to all 1s
// lower bound for right range; set 1 fill with 0s
suffixMask := uint64(math.MaxUint64<<suffixLength) | (0x5555555555555555 >> prefixLength)
zRangeR[0][0] &= suffixMask // set suffix to all 0s
zRangeR[0][0] |= 1 << (suffixLength - 1) // set first suffix bit to 1
zRangeR[0][1] &= 0x5555555555555555 << (prefixLength % 2) // set suffix to all 0s
suffixMask := uint64(math.MaxUint64<<suffixLength) | (xMask >> prefixLength)
zRangeR[0][0] &= suffixMask // set suffix to all 0s
zRangeR[0][0] |= 1 << (suffixLength - 1) // set first suffix bit to 1
zRangeR[0][1] &= xMask << (prefixLength % 2) // set suffix to all 0s
} else {
prefixLength := bits.LeadingZeros64(zl[1] ^ zh[1])
if isContinuous(zl[1], zh[1], prefixLength) {
@@ -266,11 +274,11 @@ func splitZRanges(zRange ZRange, zSize float64, zShamt, depth int, acc []ZRange)
// upper bound for left range; set 0 fill with 1s
suffixLength := 64 - prefixLength
zRangeL[1][1] |= 0xAAAAAAAAAAAAAAAA >> prefixLength // set suffix to all 1s
zRangeL[1][1] &= ^(1 << (suffixLength - 1)) // set at prefix to 0
zRangeL[1][1] |= yMask >> prefixLength // set suffix to all 1s
zRangeL[1][1] &= ^(1 << (suffixLength - 1)) // set at prefix to 0
// lower bound for right range; set 1 fill with 0s
suffixMask := uint64(math.MaxUint64<<suffixLength) | (0x5555555555555555 >> prefixLength)
suffixMask := uint64(math.MaxUint64<<suffixLength) | (xMask >> prefixLength)
zRangeR[0][1] &= suffixMask // set suffix to all 0s
zRangeR[0][1] |= 1 << (suffixLength - 1) // set at prefix to 1
}