A small innodb_buffer_pool_size contributed to one customer slow MySQL query. The comparable SQL Server workload ran quickly.
SQL SERVER – Parameter Sniffing and Bad Plan
Disabling parameter sniffing does not guarantee that a bad plan becomes good. That remains my answer to the customer question.
Parallelism in Express Edition: What the Limits Mean
Parallelism in Express Edition has its own reason code in the execution plan. This post reads that reason, shows the settings that keep a plan serial on any edition, and tests the check on a demo table.
SQL SERVER – Dirty Pages Clean Pages and the Correct Cache Commands
Clean Pages have no outstanding data-file write, while dirty pages contain unwritten changes. A customer asked which state was better.
max_column_id_used: How Many Columns a Table Once Had
The max_column_id_used column shows how many columns a table ever had. See it grow, find tables that lost columns, and avoid treating column_id as a position.
Tuning Query Cost 100% – SQL in Sixty Seconds #181
After the blog posts, lots of people asked me to build a video so here is the video discussing the topic of Tuning Query Cost 100%.
UPDATEUSAGE and Space: What It Fixes and What It Does Not
UPDATEUSAGE and space are two jobs: the command corrects page and row counts but frees no space. See a test where it finds nothing and a rebuild shrinks the table.