From 4b86522f4c327688ab66bb81e1a24e8b81805da6 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@victoriametrics.com>
Date: Thu, 13 Jul 2023 21:53:59 -0700
Subject: [PATCH] lib/mergeset: skip common prefix in binarySearchKey()
function
This should improve performance a bit when the search if performed among items with long common prefix
---
lib/mergeset/part_search.go | 44 ++++++++++++++++++++++---------------
1 file changed, 26 insertions(+), 18 deletions(-)
diff --git a/lib/mergeset/part_search.go b/lib/mergeset/part_search.go
index 65504ec156..8ee302a3cc 100644
--- a/lib/mergeset/part_search.go
+++ b/lib/mergeset/part_search.go
@@ -138,16 +138,7 @@ func (ps *partSearch) Seek(k []byte) {
items := ps.ib.items
data := ps.ib.data
cpLen := commonPrefixLen(ps.ib.commonPrefix, k)
- if cpLen > 0 {
- keySuffix := k[cpLen:]
- ps.ibItemIdx = sort.Search(len(items), func(i int) bool {
- it := items[i]
- it.Start += uint32(cpLen)
- return string(keySuffix) <= it.String(data)
- })
- } else {
- ps.ibItemIdx = binarySearchKey(data, items, k)
- }
+ ps.ibItemIdx = binarySearchKey(data, items, k, cpLen)
if ps.ibItemIdx < len(items) {
// The item has been found.
return
@@ -165,14 +156,18 @@ func (ps *partSearch) tryFastSeek(k []byte) bool {
if ps.ib == nil {
return false
}
- data := ps.ib.data
items := ps.ib.items
idx := ps.ibItemIdx
if idx >= len(items) {
// The ib is exhausted.
return false
}
- if string(k) > items[len(items)-1].String(data) {
+ cpLen := commonPrefixLen(ps.ib.commonPrefix, k)
+ suffix := k[cpLen:]
+ it := items[len(items)-1]
+ it.Start += uint32(cpLen)
+ data := ps.ib.data
+ if string(suffix) > it.String(data) {
// The item is located in next blocks.
return false
}
@@ -181,8 +176,16 @@ func (ps *partSearch) tryFastSeek(k []byte) bool {
if idx > 0 {
idx--
}
- if string(k) < items[idx].String(data) {
- if string(k) < items[0].String(data) {
+ it = items[idx]
+ it.Start += uint32(cpLen)
+ if string(suffix) < it.String(data) {
+ items = items[:idx]
+ if len(items) == 0 {
+ return false
+ }
+ it = items[0]
+ it.Start += uint32(cpLen)
+ if string(suffix) < it.String(data) {
// The item is located in previous blocks.
return false
}
@@ -190,7 +193,7 @@ func (ps *partSearch) tryFastSeek(k []byte) bool {
}
// The item is located in the current block
- ps.ibItemIdx = idx + binarySearchKey(data, items[idx:], k)
+ ps.ibItemIdx = idx + binarySearchKey(data, items[idx:], k, cpLen)
return true
}
@@ -330,11 +333,14 @@ func (ps *partSearch) readInmemoryBlock(bh *blockHeader) (*inmemoryBlock, error)
return ib, nil
}
-func binarySearchKey(data []byte, items []Item, key []byte) int {
+func binarySearchKey(data []byte, items []Item, k []byte, cpLen int) int {
if len(items) == 0 {
return 0
}
- if string(key) <= items[0].String(data) {
+ suffix := k[cpLen:]
+ it := items[0]
+ it.Start += uint32(cpLen)
+ if string(suffix) <= it.String(data) {
// Fast path - the item is the first.
return 0
}
@@ -346,7 +352,9 @@ func binarySearchKey(data []byte, items []Item, key []byte) int {
i, j := uint(0), n
for i < j {
h := uint(i+j) >> 1
- if h >= 0 && h < uint(len(items)) && string(key) > items[h].String(data) {
+ it := items[h]
+ it.Start += uint32(cpLen)
+ if h >= 0 && h < uint(len(items)) && string(suffix) > it.String(data) {
i = h + 1
} else {
j = h