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[RocksDB] Make block based table hash index more adaptive

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Summary: Currently, RocksDB returns error if a db written with prefix hash index, is later opened without providing a prefix extractor. This is uncessarily harsh. Without a prefix extractor, we could always fallback to the normal binary index.

Test Plan: unit test, also manually veried LOG that fallback did occur.

Reviewers: sdong, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D19191
This commit is contained in:
Haobo Xu 2014-06-19 15:32:31 -07:00
parent 4f5ccfd179
commit 7a9dd5f214
2 changed files with 41 additions and 7 deletions
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25
db/db_test.cc
View File

@ -6822,6 +6822,31 @@ TEST(DBTest, TailingIteratorPrefixSeek) {
ASSERT_TRUE(!iter->Valid());
}
TEST(DBTest, BlockBasedTablePrefixIndexTest) {
// create a DB with block prefix index
BlockBasedTableOptions table_options;
Options options = CurrentOptions();
table_options.index_type = BlockBasedTableOptions::kHashSearch;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
options.prefix_extractor.reset(NewFixedPrefixTransform(1));
Reopen(&options);
ASSERT_OK(Put("k1", "v1"));
Flush();
ASSERT_OK(Put("k2", "v2"));
// Reopen it without prefix extractor, make sure everything still works.
// RocksDB should just fall back to the binary index.
table_options.index_type = BlockBasedTableOptions::kBinarySearch;
options.table_factory.reset(NewBlockBasedTableFactory(table_options));
options.prefix_extractor.reset();
Reopen(&options);
ASSERT_EQ("v1", Get("k1"));
ASSERT_EQ("v2", Get("k2"));
}
TEST(DBTest, ChecksumTest) {
BlockBasedTableOptions table_options;
Options options = CurrentOptions();

23
table/block_based_table_reader.cc
View File

@ -1132,6 +1132,15 @@ Status BlockBasedTable::CreateIndexReader(IndexReader** index_reader,
auto comparator = &rep_->internal_comparator;
const Footer& footer = rep_->footer;
if (index_type_on_file == BlockBasedTableOptions::kHashSearch &&
rep_->options.prefix_extractor == nullptr) {
Log(rep_->options.info_log,
"BlockBasedTableOptions::kHashSearch requires "
"options.prefix_extractor to be set."
" Fall back to binary seach index.");
index_type_on_file = BlockBasedTableOptions::kBinarySearch;
}
switch (index_type_on_file) {
case BlockBasedTableOptions::kBinarySearch: {
return BinarySearchIndexReader::Create(
@ -1144,19 +1153,19 @@ Status BlockBasedTable::CreateIndexReader(IndexReader** index_reader,
if (meta_index_iter == nullptr) {
auto s = ReadMetaBlock(rep_, &meta_guard, &meta_iter_guard);
if (!s.ok()) {
return Status::Corruption("Unable to read the metaindex block");
// we simply fall back to binary search in case there is any
// problem with prefix hash index loading.
Log(rep_->options.info_log,
"Unable to read the metaindex block."
" Fall back to binary seach index.");
return BinarySearchIndexReader::Create(
file, footer, footer.index_handle(), env, comparator, index_reader);
}
meta_index_iter = meta_iter_guard.get();
}
// We need to wrap data with internal_prefix_transform to make sure it can
// handle prefix correctly.
if (rep_->options.prefix_extractor == nullptr) {
return Status::InvalidArgument(
"BlockBasedTableOptions::kHashSearch requires "
"options.prefix_extractor to be set.");
}
rep_->internal_prefix_transform.reset(
new InternalKeySliceTransform(rep_->options.prefix_extractor.get()));
return HashIndexReader::Create(