3. Currently, you cannot resize`ptrack` map in runtime, only on postmaster start. Also, you will loose all tracked changes, so it is recommended to do so in the maintainance window and accompany this operation with full backup. See[TODO](#TODO) for details.

4. You will need up to`ptrack.map_size * 3` of additional disk space, since`ptrack` uses two additional temporary files for durability purpose. See[TODO](#Architecture) for details.

4. You will need up to`ptrack.map_size * 3` of additional disk space, since`ptrack` uses two additional temporary files for durability purpose. See[Architecture section](#Architecture) for details.

First target was to measure`ptrack` overhead on TPS due to marking modified pages in the map in memory. We used PostgreSQL 12 cluster of approximately 1 GB size, initialized with`pgbench` on a`tmpfs` partition:

First target was to measure`ptrack` overheadinfluenceon TPS due to marking modified pages in the map in memory. We used PostgreSQL 12 (REL_12_STABLE) cluster of approximately 1 GB size, initialized with`pgbench` on a`tmpfs` partition:

pgbench -i -s 133

UPDATE large_test2SET num3= num3+1WHERE num1<20000000/5;

After that, incremental`ptrack` backups were taken with`pg_probackup` followed by full backups. Tests show that`ptrack_backup_time / full_backup_time ~= ptrack_backup_size / full_backup_size`, i.e. iftheonly 20% of data were modified, then`ptrack` backup will be 5 times faster than full backup. Thus, the overhead of building`ptrack` map during backup is minimal. Example:

After that, incremental`ptrack` backups were taken with`pg_probackup` followed by full backups. Tests show that`ptrack_backup_time / full_backup_time ~= ptrack_backup_size / full_backup_size`, i.e. if only 20% of data were modified, then`ptrack` backup will be 5 times faster than full backup. Thus, the overhead of building`ptrack` map during backup is minimal. Example:

21:02:43 postgres:~/dev/ptrack_test$time pg_probackup backup -B$(pwd)/backup --instance=node -p5432 -b ptrack --no-sync --stream

INFO: Backup start, pg_probackup version: 2.3.1, instance: node, backup ID: QAA89O, backup mode: PTRACK, wal mode: STREAM, remote: false, compress-algorithm: none, compress-level: 1

INFO: Parent backup: QAA7FL