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EXPLAIN ANALYZE is a profiling tool for your queries that will show you where MySQL spends time on your query and why. It will plan the query, instrument it and execute it while counting rows and measuring time spent at various points in the execution plan.

Under normal circumstances you don't need to analyse the table, the index cares for himself, it updates the index and stats automatically. But on high traffic tables, with lots of deletes the index gets "confused" and needs more time to select the right rows, then you run ANALYSE when no other traffic is made.

OPTIMIZE TABLE Analyzes table, stores the key distribution for a table, reclaims the unused space and defragments the data file. ANALYZE TABLE Only analyzes table and stores the key distribution.

The way analyze table helps performance is that it updates statistics that the optimizer uses to choose indexes for a given query.

ANALYZE TABLE removes the table from the table definition cache, which requires a flush lock. If there are long running statements or transactions still using the table, subsequent statements and transactions must wait for those operations to finish before the flush lock is released.

The dbms_stats procedure should always be used to analyze Oracle tables, and the "analyze" command is only for Oracle 8i and earlier. exec dbms_stats. gather_table_stats(MYOWNER, 'MYTABLE', cascade => TRUE);

When you run the ANALYZE TABLE command in Spark, it computes statistics for the table, such as the number of rows and the size of the table. These statistics are crucial for the query optimizer to make efficient decisions.

ANALYZE TABLE causes Oracle to determine how many rows are in the table and how storage is allocated. It also calculates the number of chained rows. The most important pieces of information the optimizer gets from this process are the number of rows and the number of blocks.

ANALYZE TABLE generates table statistics: ANALYZE TABLE without either HISTOGRAM clause performs a key distribution analysis and stores the distribution for the named table or tables. For MyISAM tables, ANALYZE TABLE for key distribution analysis is equivalent to using myisamchk --analyze.

The ANALYZE command runs on all the columns in the table by default using a 10% table sample. The following is an example of an ANALYZE command that is run after a successful HCAT_SYNC_OBJECTS call: ANALYZE TABLE schema. table COMPUTE STATISTICS FOR ALL COLUMNS TABLESAMPLE SYSTEM(10);