db_bench: support seek to non-exist prefix (#5163)

Summary:
Add `--seek_missing_prefix` flag to db_bench to allow benchmarking seeking to non-existing prefix. Usage example:
```
./db_bench --db=/dev/shm/db_bench --use_existing_db=false --benchmarks=fillrandom --num=100000000 --prefix_size=9 --keys_per_prefix=10
./db_bench --db=/dev/shm/db_bench --use_existing_db=true --benchmarks=seekrandom --disable_auto_compactions=true --num=100000000 --prefix_size=9 --keys_per_prefix=10 --reads=1000 --prefix_same_as_start=true --seek_missing_prefix=true
```
Also adding `--total_order_seek` and `--prefix_same_as_start` flags.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5163

Differential Revision: D14935724

Pulled By: riversand963

fbshipit-source-id: 7c41023f007febe373eb1589861f215432a9e18a
main
Yi Wu 6 years ago committed by Facebook Github Bot
parent b5cad5c986
commit b70967aac7
  1. 30
      tools/db_bench_tool.cc

@ -1090,11 +1090,20 @@ static bool ValidatePrefixSize(const char* flagname, int32_t value) {
}
return true;
}
DEFINE_int32(prefix_size, 0, "control the prefix size for HashSkipList and "
"plain table");
DEFINE_int64(keys_per_prefix, 0, "control average number of keys generated "
"per prefix, 0 means no special handling of the prefix, "
"i.e. use the prefix comes with the generated random number.");
DEFINE_bool(total_order_seek, false,
"Enable total order seek regardless of index format.");
DEFINE_bool(prefix_same_as_start, false,
"Enforce iterator to return keys with prefix same as seek key.");
DEFINE_bool(
seek_missing_prefix, false,
"Iterator seek to keys with non-exist prefixes. Require prefix_size > 8");
DEFINE_int32(memtable_insert_with_hint_prefix_size, 0,
"If non-zero, enable "
"memtable insert with hint with the given prefix size.");
@ -2529,6 +2538,17 @@ class Benchmark {
}
}
void GenerateKeyFromIntForSeek(uint64_t v, int64_t num_keys, Slice* key) {
GenerateKeyFromInt(v, num_keys, key);
if (FLAGS_seek_missing_prefix) {
assert(prefix_size_ > 8);
char* key_ptr = const_cast<char*>(key->data());
// This rely on GenerateKeyFromInt filling paddings with '0's.
// Putting a '1' will create a non-existing prefix.
key_ptr[8] = '1';
}
}
std::string GetPathForMultiple(std::string base_name, size_t id) {
if (!base_name.empty()) {
#ifndef OS_WIN
@ -4964,6 +4984,8 @@ void VerifyDBFromDB(std::string& truth_db_name) {
int64_t found = 0;
int64_t bytes = 0;
ReadOptions options(FLAGS_verify_checksum, true);
options.total_order_seek = FLAGS_total_order_seek;
options.prefix_same_as_start = FLAGS_prefix_same_as_start;
options.tailing = FLAGS_use_tailing_iterator;
Iterator* single_iter = nullptr;
@ -4988,7 +5010,8 @@ void VerifyDBFromDB(std::string& truth_db_name) {
char value_buffer[256];
while (!duration.Done(1)) {
int64_t seek_pos = thread->rand.Next() % FLAGS_num;
GenerateKeyFromInt((uint64_t)seek_pos, FLAGS_num, &key);
GenerateKeyFromIntForSeek(static_cast<uint64_t>(seek_pos), FLAGS_num,
&key);
if (FLAGS_max_scan_distance != 0) {
if (FLAGS_reverse_iterator) {
GenerateKeyFromInt(
@ -6256,6 +6279,11 @@ int db_bench_tool(int argc, char** argv) {
FLAGS_stats_interval = 1000;
}
if (FLAGS_seek_missing_prefix && FLAGS_prefix_size <= 8) {
fprintf(stderr, "prefix_size > 8 required by --seek_missing_prefix\n");
exit(1);
}
rocksdb::Benchmark benchmark;
benchmark.Run();

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