Additional Tables

The Reference Catalog includes additional tables that can be used for performance monitoring and inspection. The definition for these tables described on this page may change across SQream versions.

Extents

The extents storage object identifies storage extents, and each storage extents can contain several chunks.

Note

This is an internal table designed for low-level performance troubleshooting.

Column	Description
database_name	Shows the name of the databse containing the extent.
table_id	Shows the ID of the table containing the extent.
column_id	Shows the ID of the column containing the extent.
extent_id	Shows the ID for the extent.
size	Shows the extent size in megabytes.
path	Shows the full path to the extent on the file system.

Chunk Columns

The chunk_columns storage object lists chunk information by column.

Column	Description
database_name	Shows the name of the databse containing the extent.
table_id	Shows the ID of the table containing the extent.
column_id	Shows the ID of the column containing the extent.
chunk_id	Shows the chunk ID.
extent_id	Shows the extent ID.
compressed_size	Shows the compressed chunk size in bytes.
uncompressed_size	Shows the uncompressed chunk size in bytes.
compression_type	Shows the chunk’s actual compression scheme.
long_min	Shows the minimum numeric value in the chunk (if one exists).
long_max	Shows the maximum numeric value in the chunk (if one exists).
string_min	Shows the minimum text value in the chunk (if one exists).
string_max	Shows the maximum text value in the chunk (if one exists).
offset_in_file	Reserved for internal use.

Note

This is an internal table designed for low-level performance troubleshooting.

Chunks

The chunks storage object identifies storage chunks.

Column	Description
database_name	Shows the name of the databse containing the chunk.
table_id	Shows the ID of the table containing the chunk.
column_id	Shows the ID of the column containing the chunk.
rows_num	Shows the amount of rows in the chunk.
deletion_status	Determines what data to logically delete from the table first, and identifies how much data to delete from the chunk. The value 0 is ued for no data, 1 for some data, and 2 to delete the entire chunk.

Note

This is an internal table designed for low-level performance troubleshooting.

Delete Predicates

The delete_predicates storage object identifies the existing delete predicates that have not been cleaned up.

Each DELETE command may result in several entries in this table.

Column	Description
database_name	Shows the name of the databse containing the predicate.
table_id	Shows the ID of the table containing the predicate.
max_chunk_id	Reserved for internal use, this is a placeholder marker for the highest chunk_id logged during the DELETE operation.
delete_predicate	Identifies the DELETE predicate.

Note

This is an internal table designed for low-level performance troubleshooting.