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Segment, Column, and Merge Status Tables

This section includes information schema tables that contain information about the way data is stored and organized within a cluster.

information_schema.IND_CS_PARTITION_ROW_SEGMENT_GROUPS

This table store information about groups of row segments that are sorted together.

Column Name Description
DATABASE_NAME The name of the related database.
TABLE_NAME The name of the related table.
PARTITION The ID of the partition of a given group of row segments.
ROW_SEGEMENT_COUNT The number of row segments in a given sorted group of row segments.
ROW_COUNT The number of rows in a given sorted row segment group.
ROW_SEGMENT_MAX_ROW_COUNT The maximum number of rows in a given segment.

information_schema.KEY_COLUMN_USAGE

This table contains information about columns that are part of unique keys (constraints). It displays one row per column in a unique constraint.

Column Name Description
CONSTRAINT_CATALOG This value is always def.
CONSTRAINT_SCHEMA The name of the related schema (database) for a given key column.
CONSTRAINT_NAME The name of the related constraint for a given key column.
TABLE_CATALOG Value is always def.
TABLE_SCHEMA The name of the related schema (database) for a given key column.
TABLE_NAME The name of the related table for a given key column.
COLUMN_NAME The name of a given key column.
ORDINAL_POSITION The column’s position within the key. (These are numbered beginning with 1.)
POSITION_IN_UNIQUE_CONSTRAINT Always NULL.
REFERENCED_TABLE_SCHEMA Always NULL.
REFERENCED_TABLE_NAME Always NULL.
REFERENCED_COLUMN_NAME Always NULL.

information_schema.MV_COLUMNSTORE_SEGMENT_INDEX

This view stores information about indexes used to sort columnstore segments.

Column Name Description
DATABASE_NAME The name of the related database.
TABLE_NAME The name of the related table.
INDEX_NAME The name of a given columnstore segment’s index.
SEGMENT_ID The ID of a given columnstore segment.
FILE The name of a given columnstore file.
HOST The hostname or IP address for the related leaf node.
PORT The port number of the related leaf node.
NODE_ID The ID of the related leaf node.
PARTITION The ID of the related partition.
ENCODING The type of encoding for a given column.
UNCOMPRESSED_SIZE The uncompressed size, in MB, of a given segement index.
COMPRESSED_SIZE The compressed size, in MB, of a given segement index.
CREATION_TIME The timestamp when a given columnstore segment was created.
LSN Log sequence number of the related blob file.
TERM The term of the database, used to uniquely identify which node was the master of a specific database.
CHECKSUM The crc32c checksum of the file contents.
FILE_OFFSET Specifies the offset in the file where a given segment is stored.

information_schema.MV_COLUMNSTORE_FILES

This view stores information about columnstore files.

Column Name Description
DATABASE_NAME The name of the related database.
TABLE_NAME The name of the related table.
FILE_TYPE The type of a given columnstore file.
FILE The name of a given columnstore file.
HOST The hostname or IP address for the related leaf node.
PORT The port number of the related leaf node.
NODE_ID The ID of the related leaf node.
PARTITION The ID of the related partition.
SIZE The size, in bytes, of a given columnstore file.
CREATION_TIME The timestamp when a given columnstore file was created.
LSN Log sequence number of the related blob file.
TERM The term of the database, used to uniquely identify which node was the master of a specific database.
CHECKSUM The crc32c checksum of the file contents.

information_schema.MV_COLUMNSTORE_MERGE_STATUS

This view stores information about the status of background_merger processes for columnstore tables.

Column Name Description
DATABASE_NAME The name of the related database.
TABLE_NAME The name of the related table.
PARTITION_ID The ID of the related partition.
MERGER Specifies whether the given status is for slow, fast, manual, or index merging.
STATE The current state of the merge step: Idle, Waiting, Preparing, Merging Segments, Compacting Segments, Merging Indexes, Compacting Indexes, Updating Statistics, or Populating Altering-Encoding.
PLAN The size, in number of segments, or the rows being merged.
PROGRESS_PERCENT Merge progress represented as a number between 0 and 100.

information_schema.MV_REBALANCE_STATUS

This table contains information about the status of REBALANCE commands such as REBALANCE ALL DATABASES and REBALANCE PARTITIONS.

Column Name Description
DATABASE_NAME The name of the databse the REBALANCE command is running on or within.
ACTION The action being performed: either COPY PARTITION or PROMOTE PARTITION.
ORDINAL The ID of the related partition.
TARGET_HOST The target hostname or IP address of a REBALANCE command.
TARGET_PORT The target port number of a REBALANCE command.
PHASE The phase (group of actions occuring at the same time) that a given action is part of.
STATUS The status of the REBALANCE.
RUNNING_TIME_MS The amount of time in miliseconds spent on a given action.

MV_ROW_CHANGE_COUNTS

This table is primarily for internal use, we recommend using MV_COLLECTED_ROW_CHANGE_COUNTS instead.

This table contains information about changes to table partitions over time. Unlike the collected row change counts table, this table solely reflects the number of changes that have occurred in each partition since the SingleStore instance responsible for the partition was started. This data is asynchronously collected and used to update the collected change counts table.

Column Name Description
TABLE_NAME The name of the table.
DATABASE_NAME The name of the related database.
PARTITION The ID of the partition to which changes were made.
CHANGED The cumulative count of number of rows changed.
TOKEN An arbitrary value used to detect when instances in the cluster have been restarted