Chapter 27. Metadata Tables
Table of Contents
- 27.1.
pga_snapshotMetadata Table- 27.2.
pga_snapshot_changesMetadata Table- 27.3.
pga_schemaMetadata Table- 27.4.
pga_tableMetadata Table- 27.5.
pga_storageMetadata Table- 27.6.
pga_uriMetadata Table- 27.7.
pga_folderMetadata Table- 27.8.
pga_columnMetadata Table- 27.9.
pga_data_fileMetadata Table- 27.10.
pga_files_scheduled_for_deletionMetadata Table- 27.11.
pga_table_statsMetadata Table- 27.12.
pga_table_column_statsMetadata Table- 27.13.
pga_file_column_statisticsMetadata Table- 27.14.
pga_transaction_logMetadata Table - 27.2.
The metadata stored in metadata tables of pgpro_metastore is required for the following functionality:
Creating analytical views.
Querying analytical tables that use partitioning and indexes of Parquet files.
Supporting basic ETL operations:
performing ETL operations
scheduling ETL operations to be performed at a certain date and time, as well as sequentially (one after another)
limiting resources available for ETL operations to avoid impacting the OLTP workload
Working with the OLAP data:
creating Parquet files with the OLAP data from Postgres Pro tables and importing this data to analytical tables
exporting the OLAP data from analytical tables to Parquet, CSV, and JSON files
creating reports with filtered OLAP data using SQL queries
Making transaction updates to pgpro_metastore objects, as well as providing consistent updates of analytical tables when reading and writing to these tables.
Checking data integrity and restoring Parquet files from backups or by using S3 storage mirrors.
Monitoring pgpro_metastore and notifying administrators about events requiring their immediate attention.
Storing Parquet files in separate storages to avoid competition with the OLTP workload for I/O throughput.
The schema of metadata tables is shown in the diagram below.