System Variables

TideSQL registers the variables below. The read-only group is set at server startup and cannot change while the server runs. The dynamic global group can be changed at runtime with SET GLOBAL. The session group can be set per connection with SET SESSION (and its global value is the default new sessions inherit).

Global, read-only, set at startup

Variable	Default	Description
`tidesdb_flush_threads`	4	Background threads flushing memtables to SSTables. 0 lets the library auto-size the shared flush pool to min(CPU count, 4) at open
`tidesdb_compaction_threads`	4	Background threads running LSM compaction
`tidesdb_log_level`	TRACE	Library log level, one of TRACE, INFO, WARN, ERROR, NONE
`tidesdb_block_cache_size`	256 MB	Size in bytes of the global block cache shared across all column families
`tidesdb_max_open_sstables`	256	Maximum SSTable structures cached in the LRU. 0 means unlimited, bounded only by the process open-file limit
`tidesdb_log_to_file`	ON	Write library logs to a LOG file in the data directory instead of stderr
`tidesdb_log_truncation_at`	24 MB	Log file truncation size in bytes. 0 disables truncation
`tidesdb_memtable_write_buffer_size`	256 MB	Write buffer size in bytes for the shared memtable. 0 lets the library auto-size it
`tidesdb_memtable_sync_mode`	FULL	WAL durability for every commit, one of NONE, INTERVAL, FULL. See Durability
`tidesdb_memtable_sync_interval`	128000	WAL sync interval in microseconds, used only when the sync mode is INTERVAL
`tidesdb_memtable_skip_list_max_level`	0	Skip-list max level for the memtable. 0 keeps the library default
`tidesdb_memtable_skip_list_probability`	0.0	Skip-list level-promotion probability for the memtable. 0.0 keeps the library default
`tidesdb_vlog_segment_size`	0	Size in bytes at which the value log seals a segment and opens a fresh one. 0 keeps the library default
`tidesdb_value_separation_threshold`	0	Values at or above this size in bytes go to the shared value log instead of inline in the klog, so compaction rewrites only a reference. Database-wide, applied at open. 0 keeps the library default
`tidesdb_memtable_l0_queue_stall_threshold`	0	Sealed-memtable queue depth at which writes are paced for back-pressure. 0 keeps the library default of 16
`tidesdb_memtable_idle_flush_seconds`	-1	Seconds of write inactivity after which the shared memtable is flushed even before it fills. -1 keeps the library default
`tidesdb_txn_timeout_seconds`	-1	Seconds a transaction may run before the library aborts it. -1 keeps the library default
`tidesdb_data_home_dir`	(auto)	Directory for the data files. Defaults to `<mysql_datadir>/../tidesdb_data`

Global, dynamic

Variable	Default	Description
`tidesdb_backup_dir`	(empty)	Set to a path to trigger an online backup. Clear with an empty string. See Backup
`tidesdb_checkpoint_dir`	(empty)	Set to a path to write a consistent checkpoint copy of the data directory to, a durable flush of the WAL, value log, and manifest followed by a byte-for-byte copy. Clear with an empty string
`tidesdb_fts_min_word_len`	3	Minimum word length in characters for full-text indexing
`tidesdb_fts_max_word_len`	84	Maximum word length in characters for full-text indexing
`tidesdb_fts_bm25_k1`	1.2	BM25 k1 parameter, term-frequency saturation
`tidesdb_fts_bm25_b`	0.75	BM25 b parameter, document-length normalization from 0 to 1
`tidesdb_fts_blend_chars`	(empty)	Characters treated as both separators and word characters. Set to `'` for Italian and French elision. See Full-Text Search
`tidesdb_ft_stopword_table`	NULL	Custom stop-word table in `db_name/table_name` form. NULL uses the InnoDB default list, empty string disables stop-word filtering

Session, with a global default

These are session-scoped. Setting one globally changes the default new sessions inherit. The tidesdb_default_* group supplies the default for the matching table option when CREATE TABLE does not set it.

Variable	Default	Description
`tidesdb_ttl`	0	Per-session TTL in seconds applied to INSERT and UPDATE. 0 uses the table default. Works with `SET SESSION` and `SET STATEMENT`. See Time-To-Live
`tidesdb_skip_unique_check`	OFF	Skip uniqueness checks on the primary key and unique secondary indexes during INSERT. Safe only when the application guarantees no duplicates
`tidesdb_single_delete_primary`	OFF	Use single-delete semantics on the primary row CF for this session’s DELETEs. See Write-Path Optimizations
`tidesdb_compact_after_range_delete_min_rows`	0	After a multi-row DELETE touching at least this many rows, compact the touched primary-key range synchronously. 0 disables it
`tidesdb_default_compression`	LZ4	Default `COMPRESSION` for new tables
`tidesdb_default_bloom_filter`	ON	Default `BLOOM_FILTER` for new tables
`tidesdb_default_bloom_fpr`	100	Default `BLOOM_FPR` in parts per 10,000, 100 is 1%
`tidesdb_default_keep_values_inline`	OFF	Default `KEEP_VALUES_INLINE` for new tables
`tidesdb_default_btree_klog_block_size`	4096	Default `BTREE_KLOG_BLOCK_SIZE` in bytes for new tables. Sizing a node to the block manager first-read window avoids a second read per access
`tidesdb_default_l1_file_count_trigger`	4	Default `L1_FILE_COUNT_TRIGGER`
`tidesdb_default_level_size_ratio`	10	Default `LEVEL_SIZE_RATIO`
`tidesdb_default_min_levels`	1	Default `MIN_LEVELS`
`tidesdb_default_dividing_level_offset`	1	Default `DIVIDING_LEVEL_OFFSET`
`tidesdb_default_isolation_level`	REPEATABLE_READ	Default `ISOLATION_LEVEL`
`tidesdb_default_tombstone_density_trigger`	0	Default `TOMBSTONE_DENSITY_TRIGGER` in parts per 10,000, 0 disables it
`tidesdb_default_tombstone_density_min_entries`	1024	Default `TOMBSTONE_DENSITY_MIN_ENTRIES`

Setting defaults in my.cnf

[mysqld]
plugin-load-add=ha_tidesdb.so
tidesdb_memtable_sync_mode=NONE
tidesdb_default_compression=NONE
tidesdb_default_bloom_fpr=10
tidesdb_value_separation_threshold=64

-- new tables inherit the global defaults
CREATE TABLE t1 (id INT PRIMARY KEY) ENGINE=TIDESDB;

-- override one option for one table
CREATE TABLE t2 (id INT PRIMARY KEY) ENGINE=TIDESDB COMPRESSION='ZSTD';

-- change a default for this session only
SET SESSION tidesdb_default_bloom_fpr = 50;