Topic
MongoDBBeginnerA server selection timeout means the driver can't reach the cluster; a pool timeout means you've run out of connections. How to diagnose each, including the serverless one-client-per-request trap.
#configuration#nosql#troubleshooting
MySQLBeginnerThe error points at a query that returned arbitrary values. Fix it with aggregates, primary-key grouping, ANY_VALUE() or window functions, and keep the SQL mode on.
#configuration#troubleshooting
MilvusBeginner"Collection not loaded" and missing new rows come from load state and the default Bounded consistency level. How to fix both, and why flush() after every insert isn't the answer.
#configuration#troubleshooting#vector-search
RedisBeginnerWhat to cache, string vs hash, key naming, how TTLs and expiry work, maxmemory and every eviction policy, a working cache-aside example, and the commands to measure and secure a Redis cache.
#caching#configuration#nosql
Valkey is the BSD-licensed fork of Redis 7.2. What's compatible, what has diverged since, how to migrate with replication, and when staying on Redis makes more sense.
#caching#configuration#nosql
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
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 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
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
RedisIntermediateWrites fail and reads still work. Understand Redis eviction policies, find what's filling memory, and pick the right fix depending on whether Redis is a cache or a datastore.
#caching#configuration#nosql
MySQLBeginnerMySQL's utf8 isn't real UTF-8. Here's why emoji break it, how to convert tables and connections to utf8mb4, and how to get past the 767-byte index limit.
#configuration#data-types#troubleshooting
