Missing database indexes and unoptimized queries cause severe production slowdowns
8/10 HighCommon mistakes include missing database indexes on frequently queried columns, fetching entire tables instead of specific rows, and not using connection pooling. Queries that work fine in development with 100 rows can take 3+ seconds in production with 50,000 rows and no indexes instead of 30 milliseconds.
Sources
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Poor database connection handling can lead to performance bottlenecks, data inconsistencies, or even crashes. Writing efficient SQL queries and handling database connections can be complex, especially when dealing with large datasets.
Slow queries may be due to: lack of indexes, large datasets without optimization, suboptimal query structures... SELECT * in queries to retrieve all columns from a table, but this can lead to unnecessary data fetching, reducing performance.
slow running queries... most common symptom is what we will say is whenever you try to debug the query... if stats are out outdated then query will start giving you... optimizer will generate a bad plans... the data has been grow and now whatever the index... it is not actually working
Other common mistakes include missing database indexes on columns you frequently cury, fetching entire tables when you only need 10 rows, and not using connection pooling. So your app creates new database connection on every request. You might think your queries are fast because they work fine in development with 100 rows of test data, but in production with 50,000 rows and no indexes, that same query takes 3 seconds instead of 30 milliseconds.