Partition pruning.

also: time-based partitioning · date partitioning · partition elimination

Splitting tables by a column (usually date) so a query's filter lets the engine skip every partition it can't need.

the two-minute refresher

Daily partitions + WHERE date in January = read 31 partitions, skip 334.
Choose granularity by query pattern; aim for about 100 MB to 1 GB per partition.
Hash partitions on user_id make single-user queries read one partition.
Queries that don't filter on the partition column get no benefit.

also: time-based partitioning · date partitioning · partition elimination

Splitting tables by a column (usually date) so a query's filter lets the engine skip every partition it can't need.

Daily partitions + WHERE date in January = read 31 partitions, skip 334.
Choose granularity by query pattern; aim for about 100 MB to 1 GB per partition.
Hash partitions on user_id make single-user queries read one partition.
Queries that don't filter on the partition column get no benefit.