12 min read
MySQL Generated Invisible Primary Keys: GIPK Mode in Production
PK-less InnoDB tables silently tax replication and tooling. GIPK mode fixes them at CREATE TABLE time, if you know what my_row_id changes and what it quietly breaks.
PostgreSQL Field Notes
Notes for the problems that show up after launch: bad plans, awkward migrations, index debt, vacuum pressure, replica lag, and the small decisions that make PostgreSQL easier to operate.
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11 min read
InnoDB Compression: ROW_FORMAT=COMPRESSED vs Transparent Page Compression
MySQL ships two unrelated features both called InnoDB compression, and picking the wrong one costs memory, CPU, or both. Here is how each actually works and when either still pays.
12 min read
MySQL Replication Filters: replicate-do-db, binlog-do-db, and Silent Divergence
Replication filters diverge replicas without raising a single error, and source-side filters quietly gut your point-in-time recovery. Here is how each layer actually fails.
11 min read
innodb_io_capacity and Flushing: Tuning InnoDB's Dirty-Page Pipeline
innodb_io_capacity is a background I/O budget, not a speed dial. Crank it past your redo-driven need and the page cleaner spends the surplus evicting warm pages you were about to read.
12 min read
MySQL Hash Join vs Nested Loop: What 8.0 Changed in Join Tuning
MySQL 8.0 replaced block nested loop with a real hash join, and half the join-tuning advice from the 5.7 era is now wrong. When the optimizer hashes, when an index beats it, and when it loses.
11 min read
MySQL Descending Indexes: Mixed-Direction Composites Done Right
ORDER BY col1 ASC, col2 DESC forced a filesort for two decades of MySQL. Since 8.0, a composite with a real descending part resolves it straight from the index — if the directions match exactly.
12 min read
InnoDB Read-Only Transactions: The Fast Path Your ORM Is Wasting
InnoDB skips transaction bookkeeping for known read-only transactions — but an open read view still pins purge. The autocommit=0 ORM trap, replica read-only flags, and how to measure the win.
11 min read
innodb_dedicated_server: What Auto-Sizing Sets and When to Opt Out
innodb_dedicated_server sizes your buffer pool and redo from detected hardware. On a truly dedicated box it is right; inside a memory-limited container it can size you straight into an OOM kill.
12 min read
MySQL Prepared Statements: The Per-Connection Cost Nobody Budgets
Prepared statements are per-connection state with a server-wide cap. Prepared_stmt_count, error 1461, the ORM leak pattern, and why per-query prepare is the worst of both protocols.
11 min read
MySQL Undo Tablespaces: Why They Grow and How Truncation Reclaims Space
Undo growth means a snapshot is pinning purge. How innodb_undo_log_truncate reclaims space, managing tablespaces with CREATE and DROP UNDO TABLESPACE, and the stuck-report incident shape.
12 min read
MySQL innodb_autoinc_lock_mode: What 0, 1, and 2 Really Serialize
Mode 0 holds a table lock to the end of every insert, mode 1 only for bulk loads, mode 2 never. Why 8.0 defaults to 2, what that does to statement-based replication, and how to stop fearing ID gaps.
11 min read
MySQL 8.0 Atomic DDL and the Data Dictionary: Life After .frm Files
A crash mid-ALTER on 5.7 left orphaned #sql tables and dictionary mismatches you fixed with file surgery. MySQL 8.0's transactional data dictionary ended that era — and quietly retired a few other habits.