Metadata persistence

Overview

Memurai SQL creates in-memory indexes for your data stored in Memurai (or Valkey), and such indexes are not currently persisted on disk. However, Memurai SQL can persist the indexes metadata (names of indexes, prefixes, names and types of columns, etc.)

Memurai SQL metadata

With metadata persistence switched ON, Memurai SQL can find the metadata about the indexes that were created. Therefore, the next time you start Memurai SQL, it remembers the indexes you created in the past, and automatically repopulates them by fetching data from Memurai (or Valkey).

Metadata files

With metadata_persistence set to ON, the following files are stored on disk:

master.tids: A binary file with a list of the index tables and their TIDs (Table IDs).

idxtable_?.meta: For each index that was set up by using the MSQL.CREATE command, an idxtable_?.meta file is created. For example, if there were five indexes created, the following meta files will be listed in the metadata folder:

idxtable_1.meta
idxtable_2.meta
idxtable_3.meta
idxtable_4.meta
idxtable_5.meta

Each of the above meta files is a binary file containing the index table info, such as name, prefix, and list of columns with types.