Highlights

• Materialized Views
  • Faster updates under high contention: views which update frequently (multiple times per second) will now use significantly less resources and have reduced refresh latency.
  • Faster historical refreshes: views with very small SAMPLE BY units will now refresh much more quickly, especially for historical or full refreshes.
• TTL
  • Additional safety checks: TTL will now use min(maxTimestamp, wallClockTime) as the predicate for dropping old partitions, rather than just maxTimestamp. This avoids accidental partition drops when erroneous timestamps are written to the table.
• SQL
  • Faster (de)allocations: Memory deallocations have been sped up significantly, with jemalloc now enabled by default on Linux builds. This particularly helps for reducing query tail latencies.
  • Faster query compilation: Query parsing performance has been improved by around ~4x. This reduces latency for lightweight and fast-to-execute queries, and maximises concurrent QPS when prepared statements are not used.
  • Faster single-key GROUP BY: GROUP BY queries that group by a single key will now execute ~2-3x faster.
    • e.g. SELECT symbol, count() as count FROM trades GROUP BY symbol ORDER BY count DESC LIMIT 10;
  • Faster non-keyed averages: Keyless GROUP BY queries will now execute ~1.3x faster.
    • e.g. SELECT AVG(price) FROM trades;
  • Decimal fills: SAMPLE BY with FILL now properly supports the new DECIMAL type.

Changelist

• fix(core): fix missing partition dir on table reader open when writing identical data with dedup by @ideoma in https://github.com/questdb/questdb/pull/6479
• fix(sql): crash when using parallel ORDER BY with LIMIT and JIT filter by @puzpuzpuz in https://github.com/questdb/questdb/pull/6482
• fix(ui): remove line ending declarations from web console assembly descriptor by @emrberk in https://github.com/questdb/questdb/pull/6490
• feat(core): hints for handling histogram out of bounds error for approx_percentile()/approx_median() by @peter007-cmd in https://github.com/questdb/questdb/pull/6446
• perf(sql): use unordered maps only in single-column case by @puzpuzpuz in https://github.com/questdb/questdb/pull/6481
• fix(sql): fix parquet export bug when SQL contains now() function by @kafka1991 in https://github.com/questdb/questdb/pull/6499
• fix(sql): fix empty result set from limit queries by @bluestreak01 in https://github.com/questdb/questdb/pull/6504
• fix(sql): fix potential crash when ORDER BY symbol column added via ALTER TABLE ADD COLUMN by @kafka1991 in https://github.com/questdb/questdb/pull/6505
• fix(sql): improve refresh step estimation for sparse data with small sample by interval by @kafka1991 in https://github.com/questdb/questdb/pull/6517
• chore(utils): update async-profiler to 4.2.1 by @jerrinot in https://github.com/questdb/questdb/pull/6473
• fix(core): data corruption after range replace on column top partition by @puzpuzpuz in https://github.com/questdb/questdb/pull/6519
• fix(http): correct HTTP content length for JSON responses by @kafka1991 in https://github.com/questdb/questdb/pull/6520
• perf(core): optimize mat view writing by skipping transactions that are fully replaced by future commits or full refresh (2) by @ideoma in https://github.com/questdb/questdb/pull/6495
• fix(core): fix bad connection state after TLS session initialization failure by @jerrinot in https://github.com/questdb/questdb/pull/6529
• fix(sql): fix potential unexpected exception when parquet file schema changed in read_parquet() by @kafka1991 in https://github.com/questdb/questdb/pull/6513
• feat(core): use wall clock for TTL to prevent accidental data loss by @bluestreak01 in https://github.com/questdb/questdb/pull/6531
• fix(sql): support for decimal types in group by fill and selected cursor by @RaphDal in https://github.com/questdb/questdb/pull/6532
• fix(sql): not to ignore outer limit if a subquery has a filter and another limit by @glasstiger in https://github.com/questdb/questdb/pull/6533
• perf(sql): reduce query latency from memory deallocation overhead on Linux x86_64 by @jerrinot in https://github.com/questdb/questdb/pull/6477
• fix(sql): fix symbol column nullValue flag when adding column to non-empty table by @kafka1991 in https://github.com/questdb/questdb/pull/6507
• perf(sql): improve latency of parsing SQL expressions by @bluestreak01 in https://github.com/questdb/questdb/pull/6538
• perf(sql): speed up avg() functions in non-keyed GROUP BY queries by @puzpuzpuz in https://github.com/questdb/questdb/pull/6542
• fix(core): UPDATE to work with bind variables for TIMESTAMP columns by @glasstiger in https://github.com/questdb/questdb/pull/6510
• fix(sql): allow aggregate functions inside CASE expressions by @bluestreak01 in https://github.com/questdb/questdb/pull/6550

New Contributors

• @peter007-cmd made their first contribution in https://github.com/questdb/questdb/pull/6446

Full Changelog: https://github.com/questdb/questdb/compare/9.2.2...9.2.3