public Interface RowCountable

Get the total estimated number of rows in the container.

The number is a rough estimate and may be grossly off. In general the server will cache the row count and then occasionally write the count unlogged to a backing store. If the system happens to shutdown before the store gets a chance to update the row count it may wander from reality.

For btree conglomerates this call will return the count of both user rows and internal implementaation rows. The "BTREE" implementation generates 1 internal implementation row for each page in the btree, and it generates 1 internal implementation row for each branch row. For this reason it is recommended that clients if possible use the count of rows in the heap table to estimate the number of rows in the index rather than use the index estimated row count.

Returns:long

The total estimated number of rows in the conglomerate.

Exceptions

StandardException:

Standard exception policy.

Set the total estimated number of rows in the container.

Often, after a scan, the client of RawStore has a much better estimate of the number of rows in the container than what store has. Currently, a scan, followed by an update of the estimate, will be performed when:

• running SYSCS_UTIL.SYSCS_UPDATE_STATISTICS
• the automatic update of index statistics kicks in (see IndexStatisticsDaemon)
• performing table scans
• creating an index on a populated table

This routine can also be used to set the estimated row count in the index to the number of rows in the base table, another workaround for the problem that index estimated row count includes non-user rows.

Parameters

count:long

the estimated number of rows in the container.

Exceptions

StandardException:

Standard exception policy.