Topic
DuckDBIntermediateDuckDB can spill to disk, but memory_limit, temp_directory, insertion order and thread count decide whether it does. Settings and query patterns that prevent OOM errors.
#configuration#performance#troubleshooting
Fast until you add a filter? Create payload indexes before loading data so the filterable HNSW can use them, and set up multi-tenant collections the right way.
#indexing#performance#vector-search
MongoDBIntermediateHow to design a MongoDB schema from the workload, the hard limits that constrain it, and seven anti-patterns with a way to detect and fix each.
#data-modeling#nosql#performance
SQL ServerIntermediateA diagnostic catalogue of slow query causes in SQL Server: how to tell running from waiting, the plan or wait signature of each cause, and the fix.
#execution-plans#performance#troubleshooting
SnowflakeIntermediateYou pay for warehouse run time, not query work. Find where the credits go, fix auto-suspend and warehouse sizes, and add resource monitors before the next invoice.
#configuration#cost-optimization#performance
SQL ServerIntermediateA query-first method: find the expensive queries, read the plan for signs the missing index DMVs never report, build the index online safely, then verify and roll back.
#execution-plans#indexing#performance
SQL ServerIntermediateHow to measure SQL Server query performance with Query Store, DMVs and Extended Events, pick targets by total resource use, and check the settings that affect every query.
#configuration#db-administration#execution-plans
SQL ServerIntermediateQuery sys.dm_db_missing_index_details and its companion DMVs, read the numbers critically, find the queries behind each suggestion and merge them into the few indexes worth creating.
#db-administration#execution-plans#indexing
ClickHouseIntermediateTOO_MANY_PARTS means too many small inserts, not too much data. Batch your writes, turn on async inserts, and stop over-partitioning your MergeTree tables.
#configuration#performance#troubleshooting
SQL ServerAdvancedA table-by-table workflow for tuning existing SQL Server indexes: find unused and overlapping indexes, merge them, and replace blanket rebuilds with statistics updates.
#db-administration#indexing#maintenance
PostgreSQLAdvancedExplains by mechanism where InnoDB or PostgreSQL does less work for lookups, updates, joins, connections and replication, then shows how to benchmark your own workload with pgbench and sysbench.
#internals#mvcc#performance
