Read a PostgreSQL EXPLAIN plan before adding an index
Find the expensive step and distinguish estimates from measurements.
PostgreSQL / SQL / Performance
TECHNOLOGY / KNOWLEDGE / PRACTICE
Search results: Query Plan
Materials on AI, Python, Git, SQL, SAP/ERP, statistics and time series: explanations, examples, practical tips, sources and applicability limits.
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PostgreSQL foreign keys: NO ACTION timing and selective SET NULL
A closer look at explicitly deferred NO ACTION checks and clearing only the optional component of a composite foreign key. These details complement the basic choice between RESTRICT, CASCADE and SET NULL.
postgresql / foreign-key / on-delete / data-retention / cascade / restrict / set-null / referential-integrity
Using LIMIT and OFFSET in PostgreSQL: Best Practices, Performance Impacts, and Alternatives
LIMIT caps returned rows; OFFSET skips rows in the query result. SQL does not require ORDER BY syntactically, but repeatable page boundaries need a unique ordering. For an API, choose between page-number navigation and continuation from the last key; neither strategy alone provides a snapshot. Measure deeper pages before setting a performance cutoff.
PostgreSQL / database pagination / LIMIT / OFFSET / cursor-based pagination / query performance
Choose a PostgreSQL foreign-key deletion policy without losing the wrong rows
Compare RESTRICT, CASCADE and SET NULL using a small isolated example, then check the actual constraint and dependent rows before changing real data.
PostgreSQL / SQL / Foreign keys / Transactions
Latest row per group in PostgreSQL: make row_number ordering deterministic
Select one whole event per account with an explicit tie-breaker and a deliberate policy for missing timestamps.
data
SQL: WHERE vs HAVING - Difference in Row and Group Filtering
A detailed technical breakdown of the differences between WHERE and HAVING clauses, focusing on execution order, aggregate function compatibility, and performance optimization strategies.
SQL / PostgreSQL / Database / Query Optimization / Data Analysis
Why JOIN Multiplies Rows: Matching Keys, Constraints and Output Grain
Diagnose repeated JOIN rows by counting matching keys, checking constraints and choosing whether the result should contain orders, items or summaries.
SQL / JOIN / PostgreSQL