https://lukehebert.com/tag/sql/Recent content in Sql on Luke HebertHugoen-usWed, 02 Jul 2025 00:00:00 +0000https://lukehebert.com/post/pgbackrest-and-helpful-commands/Wed, 02 Jul 2025 00:00:00 +0000https://lukehebert.com/post/pgbackrest-and-helpful-commands/A practical reference for pgBackRest backup, restore, and cleanup commands for PostgreSQL. Covers manual cleanup, incremental backups, retention policies, and stanza management.https://lukehebert.com/post/graph-database-white-papers/Mon, 14 Apr 2025 00:00:00 +0000https://lukehebert.com/post/graph-database-white-papers/An overview of graph databases, their structure, and advantages over relational models. Covers how nodes, relationships, and the Cypher query language work together to model complex data.https://lukehebert.com/post/posgres-per-table-autovacuum-management/Mon, 28 Oct 2024 00:00:00 +0000https://lukehebert.com/post/posgres-per-table-autovacuum-management/Tune Postgres per-table autovacuum settings and track them with a single SQL view. Covers global defaults, table-specific overrides, and a ready-to-use monitoring query.https://lukehebert.com/post/how-to-get-the-most-out-of-postgres-memory-settings/Wed, 12 Jun 2024 00:00:00 +0000https://lukehebert.com/post/how-to-get-the-most-out-of-postgres-memory-settings/A practical guide to tuning Postgres memory parameters including shared_buffers, work_mem, and maintenance_work_mem. Learn how to measure actual usage, avoid out-of-memory crashes, and balance allocations for optimal performance.https://lukehebert.com/post/how-to-clean-up-pg-wal-if-the-disk-is-full/Mon, 04 Dec 2023 00:00:00 +0000https://lukehebert.com/post/how-to-clean-up-pg-wal-if-the-disk-is-full/A practical guide to resolving PostgreSQL pg_wal disk-full issues, covering both reactive recovery steps and proactive measures to prevent recurrence. Learn how to free space, move the WAL directory, and configure archiving correctly.https://lukehebert.com/post/optimize-postgresql-server-performance-through-configuration/Thu, 27 Apr 2023 00:00:00 +0000https://lukehebert.com/post/optimize-postgresql-server-performance-through-configuration/This guide walks through four key PostgreSQL configuration settings that significantly impact server performance. Learn how to tune shared_buffers, wal_buffers, effective_cache_size, and work_mem for your specific workload.https://lukehebert.com/post/postgresql-shared-memory-huge-pages/Wed, 26 Apr 2023 00:00:00 +0000https://lukehebert.com/post/postgresql-shared-memory-huge-pages/Calculating the right number of Linux huge pages for PostgreSQL is trickier than just dividing shared_buffers by the page size. This walkthrough shows how to use tuned to manage allocation and why you need to round up based on actual memory usage.https://lukehebert.com/post/postgresql-wal-retention-and-clean-up-pg-archivecleanup/Fri, 21 Apr 2023 00:00:00 +0000https://lukehebert.com/post/postgresql-wal-retention-and-clean-up-pg-archivecleanup/A practical guide to managing PostgreSQL WAL retention using the pg_archivecleanup utility, covering dry-run and delete modes, retention criteria, and a code walkthrough for novice users.https://lukehebert.com/post/using-sqlline-to-test-jdbc-connectors/Thu, 15 Dec 2022 00:00:00 +0000https://lukehebert.com/post/using-sqlline-to-test-jdbc-connectors/A practical guide to using SQLline to replicate SQL client behavior when testing JDBC connectors. Covers downloading the tool, setting up the classpath, and connecting to an Azure MySQL instance.https://lukehebert.com/post/check-database-and-optimize-everything-all-databases/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/check-database-and-optimize-everything-all-databases/A quick reference for running mysqlcheck to verify and optimize MySQL databases, including the -A flag to target every database on the server in one pass.https://lukehebert.com/post/check-mysql-user-permissions/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/check-mysql-user-permissions/A quick way to inspect what SELECT and UPDATE privileges a MySQL user actually holds, straight from the mysql.user table. Useful when an application is throwing permission errors and you need to confirm what the account can and cannot do.https://lukehebert.com/post/create-symbols-and-resolve-stack-mysql/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/create-symbols-and-resolve-stack-mysql/Learn how to extract dynamic symbols from the mysqld binary and use them to resolve a crash stack dump into readable function names.https://lukehebert.com/post/force-mysql-logs-to-file/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/force-mysql-logs-to-file/Learn how to configure MySQL’s log_output variable to write slow query and general logs to files instead of tables, and why that matters for performance and log management.https://lukehebert.com/post/galera-cluster-performance/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/galera-cluster-performance/Tuning Galera’s gcache size and page size can reduce disk I/O during replication and keep write-set lookups in memory. A quick configuration change that pays off on busy clusters.https://lukehebert.com/post/myisamchk/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/myisamchk/A quick reference for repairing corrupted MyISAM index files with myisamchk, including the exact command and what to expect when running it against a database directory.https://lukehebert.com/post/mysql-fragmentation-levels/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/mysql-fragmentation-levels/Learn how to measure InnoDB table fragmentation using information_schema queries and interpret the resulting ratio to decide when a table needs optimization.https://lukehebert.com/post/mysql-general-log/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/mysql-general-log/A quick walkthrough of enabling, configuring, and querying the MySQL general log to capture every statement that hits your server.https://lukehebert.com/post/mysql-grants/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/mysql-grants/A quick reference for viewing and applying MySQL GRANT statements, including the specific privileges needed for routine and view management.https://lukehebert.com/post/mysql-joins/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/mysql-joins/A quick reference for the four types of SQL JOIN operations in MySQL, with plain-language explanations and a simple example for each.https://lukehebert.com/post/percona-xtradb-recovery/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/percona-xtradb-recovery/Percona XtraDB Cluster can recover a crashed node and rejoin it to the cluster using an incremental state transfer. This post walks through how GTID-based position recovery works under the hood and what you will see in the error log during the process.https://lukehebert.com/post/show-global-maximum-sql-connections-in-use/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/show-global-maximum-sql-connections-in-use/A quick MySQL command to check the peak number of simultaneous connections your server has handled, useful for capacity planning and diagnosing connection bottlenecks.https://lukehebert.com/post/user-performance-data-on-mysql/Mon, 24 Jan 2022 00:00:00 +0000https://lukehebert.com/post/user-performance-data-on-mysql/A quick bash one-liner that pulls per-user CPU time, connection counts, and active session details from MySQL’s INFORMATION_SCHEMA and processlist tables.https://lukehebert.com/post/hive-bundle-logs/Thu, 19 Aug 2021 00:00:00 +0000https://lukehebert.com/post/hive-bundle-logs/Hive bundle logs in a cloud data warehouse are stored under a predictable S3 path. Knowing where to look saves time when troubleshooting query performance or diagnosing failed jobs.https://lukehebert.com/post/mysql-key-constraints-fk-by-db/Tue, 27 Jun 2017 00:00:00 +0000https://lukehebert.com/post/mysql-key-constraints-fk-by-db/A quick reference for querying MySQL information_schema to list all foreign key constraints in a given database, including the referencing and referenced columns.