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Cartoon of a calm figure in a dark suit sitting for an interview, with a wall of hundreds of unlabelled filing drawers behind it.

The Query Optimizer Interview: Twenty Minutes, No Hints

October 21, 2026
Pinal Dave
SQL Performance
Best Practices, Developer, SQL Performance, SQL Server

The query optimizer sat down for twenty minutes and answered for itself. Why it ignored your index, why one procedure gets a plan built for the wrong caller, what it does when it cannot see your value, and the moment its own plan admits it stopped looking.

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Ink spot illustration of an opened letter lying flat with a brass letter opener across one corner and a glass inkwell beside it.

The SQL Advisor: Seven Answers, All Measured

October 19, 2026
Pinal Dave
SQL Tips and Tricks
Best Practices, Database, Developer, SQL Server

The SQL Advisor answers seven letters with measurements instead of opinions. Table variables, what each index costs on insert, shrinking after a big delete, SELECT star, ORDER BY in a view, heaps, and whether the order of your WHERE predicates matters.

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Profile card for PAGEIOLATCH_SH. Blamed for slow disks. Actually means the query is waiting for a page read to finish. Caused by scattered reads on a cold cache. What to do: look at the access pattern before you blame the storage.

Know Your Wait Types: Six Profiles, All Induced

October 16, 2026
Pinal Dave
SQL Performance
Best Practices, Developer, SQL Performance, SQL Server

I caused six wait types on purpose, one at a time, and measured each one for a single session. What each is blamed for, what it actually means, and the numbers it produced on SQL Server 2025. Wait types are the most misread figures in the product.

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Diagram titled One row, one DELETE, five places it still lives. The left panel lists the row alive: a 284 byte log record before the commit, an address at 1 colon 392 colon 0, a checkpoint writing the page, and a backup copying it out. The right panel lists what remains after the delete: the ghost record still 184 bytes, log records, the statistics histogram that names the row, deallocated pages, and every backup.

The Migration of a Row: Tagged, Followed, Found Again

September 21, 2026
Pinal Dave
SQL Tips and Tricks
Best Practices, Database, Developer, SQL Server

I followed the migration of a row through SQL Server 2025, from the first write to the grave. The log gets there before the table. The delete does not erase anything. And when the table is empty and the ghost is gone, the statistics histogram still names the row in full.

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UPDATE Without WHERE, SQL in Sixty Seconds episode 211, featuring Dex and Mia.

UPDATE Without WHERE Clause: The Day Everyone Got a Raise

September 8, 2026
Pinal Dave
SQL Video
SQL in Sixty Seconds, SQL Server, SQL Transactions

An UPDATE without WHERE clause changed 8,432 salaries. When ROLLBACK can help, and how to check the affected row count before COMMIT.

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SQL Server Deadlock: Build One With Your Own Hands

SQL Server Deadlock: Build One With Your Own Hands

August 4, 2026
Pinal Dave
SQL Performance
Deadlock, SQL Server

A SQL Server deadlock occurs when sessions form a cycle of dependencies and none can continue. This example lets you create the cycle, inspect it, and remove it.

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Five potted ferns drawing water through cotton wicks from a glass bowl, a hand testing the soil of the last pot

Holiday Change Freeze Checklist for SQL Server: What to Verify First

December 25, 2024
Pinal Dave
SQL Tips and Tricks
Best Practices, Change Data Capture, SQL Server

Use a change freeze checklist for SQL Server to verify backups, integrity checks, disk headroom, Agent jobs, and serious errors.

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