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[RocksDB] [Performance Branch] Some Changes to PlainTable format

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Summary:
Some changes to PlainTable format:
(1) support variable key length
(2) use user defined slice transformer to extract prefixes
(3) Run some test cases against PlainTable in db_test and table_test

Test Plan: test db_test

Reviewers: haobo, kailiu

CC: dhruba, igor, leveldb, nkg-

Differential Revision: https://reviews.facebook.net/D14457
This commit is contained in:
Siying Dong
2013-12-20 09:35:24 -08:00
parent 28c24de8be
commit abaf26266d
15 changed files with 736 additions and 378 deletions
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45
include/rocksdb/plain_table_factory.h
View File

@@ -23,41 +23,37 @@ class TableBuilder;
// IndexedTable requires fixed length key, configured as a constructor
// parameter of the factory class. Output file format:
// +-------------+
// | version |
// +-------------+------------------------------+ <= key1 offset
// | key1 | value_size (4 bytes) | |
// +----------------------------------------+ |
// +-------------+-----------------+
// | version | user_key_length |
// +------------++------------------------------+ <= key1 offset
// | [key_size] | key1 | value_size | |
// +------------+-------------+-------------+ |
// | value1 |
// | |
// +----------------------------------------+---+ <= key2 offset
// | key2 | value_size (4 bytes) | |
// +----------------------------------------+ |
// | [key_size] | key2 | value_size | |
// +------------+-------------+-------------+ |
// | value2 |
// | |
// | ...... |
// +-----------------+--------------------------+ <= index_block_offset
// | key1 | key1 offset (8 bytes) |
// +-----------------+--------------------------+
// | key2 | key2 offset (8 bytes) |
// +-----------------+--------------------------+
// | key3 | key3 offset (8 bytes) |
// +-----------------+--------------------------+
// | ...... |
// +-----------------+------------+-------------+
// If user_key_length = kVariableLength, it means the key is variable length,
// there will be an extra field for key size encoded before every key.
class PlainTableFactory: public TableFactory {
public:
~PlainTableFactory() {
}
// user_key_size is the length of the user key. key_prefix_len is the
// length of the prefix used for in-memory indexes. bloom_num_bits is
// user_key_size is the length of the user key. If it is set to be
// kVariableLength, then it means variable length. Otherwise, all the
// keys need to have the fix length of this value. bloom_num_bits is
// number of bits used for bloom filer per key. hash_table_ratio is
// the desired ultilization of the hash table used for prefix hashing.
// the desired utilization of the hash table used for prefix hashing.
// hash_table_ratio = number of prefixes / #buckets in the hash table
PlainTableFactory(int user_key_size, int key_prefix_len,
int bloom_num_bits = 0, double hash_table_ratio = 0.75) :
user_key_size_(user_key_size), key_prefix_len_(key_prefix_len),
bloom_num_bits_(bloom_num_bits), hash_table_ratio_(hash_table_ratio) {
explicit PlainTableFactory(uint32_t user_key_len = kVariableLength,
int bloom_num_bits = 0,
double hash_table_ratio = 0.75) :
user_key_len_(user_key_len), bloom_num_bits_(bloom_num_bits),
hash_table_ratio_(hash_table_ratio) {
}
const char* Name() const override {
return "PlainTable";
@@ -70,9 +66,10 @@ public:
TableBuilder* GetTableBuilder(const Options& options, WritableFile* file,
CompressionType compression_type) const
override;
static const uint32_t kVariableLength = 0;
private:
int user_key_size_;
int key_prefix_len_;
uint32_t user_key_len_;
int bloom_num_bits_;
double hash_table_ratio_;
};

6
include/rocksdb/table_properties.h
View File

@@ -37,6 +37,10 @@ struct TableProperties {
uint64_t num_data_blocks = 0;
// the number of entries in this table
uint64_t num_entries = 0;
// format version, reserved for backward compatibility
uint64_t format_version = 0;
// If 0, key is variable length. Otherwise number of bytes for each key.
uint64_t fixed_key_len = 0;
// The name of the filter policy used in this table.
// If no filter policy is used, `filter_policy_name` will be an empty string.
@@ -61,6 +65,8 @@ struct TablePropertiesNames {
static const std::string kRawValueSize;
static const std::string kNumDataBlocks;
static const std::string kNumEntries;
static const std::string kFormatVersion;
static const std::string kFixedKeyLen;
static const std::string kFilterPolicy;
};