DFEWCCAlgo – Explain operator for invocations of the Weakly Connected Components algorithm, which finds the weakly-connected components in a directed graph. SolutionInjection – Appears before everything else in the explain output, with a value of one in theUnits Outcolumn. However, it serves a...
Seq Scan Using Clustering_index is usually used with Filter. Filter is a child node and lists the hit indexes. Filter can be a clustering filter, segment filter, or bitmap filter. For more information, see Column-oriented storage. Example 1: A query hits indexes. BEGIN; CREATE TABLE ...
unionM,N: The row refers to the union of the rows with id values of M and N. derivedN: The row refers to the derived table result for the row with an id value of N. A derived table may result, for example, from a subquery in the FROM clause. subqueryN: The row refers to the...
The following example returns the query plan for a CREATE TABLE AS (CTAS) statement: explaincreatetablevenue_nonullsasselect*fromvenuewherevenueseatsisnotnull; QUERY PLAN---XN Seq Scanonvenue (cost=0.00..2.02rows=187width=45)Filter: (venueseatsISNOTNULL) (2rows) Yes No Provide feedback...
"join_algorithm": "nested_loop", "actual_last_row_ms": 5071.693038, "actual_first_row_ms": 2.071419, "estimated_total_cost": 49827.83951582908 } With EXPLAIN ANALYZE we get a few extra fields starting with "actual_", which contain information about the execution. In the TREE format these ...
See Using Buffer UPDATE Algorithm for a detailed explanation. EXPLAIN EXTENDED The EXTENDED keyword adds another column, filtered, to the output. This is a percentage estimate of the table rows that will be filtered by the condition. An EXPLAIN EXTENDED will always throw a warning, as it adds...
INDEX FULL SCAN BE_IX This example is also interesting in that it has a NOSORT function. The group by does not need to sort because the index row source is already pre sorted. Views When a view cannot be merged into the main query you will often see a projection view operation. This...
For example in the plan in Figure32, the parallel join between the SALES and CUSTOMERS uses two sets of parallel server processes. The producers scan the two tables, applying any where clause predicates and send the resulting rows to the consumers (lines 9-11 21 THE ORACLE OPTIMIZER EXPLAIN ...
Hash joins are available beginning with MySQL 8.0.18; the Block Nested-Loop algorithm is not used in MySQL 8.0.20 or later MySQL releases. For more information about these optimizations, see Section 10.2.1.4, “Hash Join Optimization”, and Block Nested-Loop Join Algorithm. See Batched Key...
by hash(Orange box)The router, which is a component that takes one stream of input rows and sends them to a node according to a routing algorithm. For example, a hash router hashes columns of a row and sends the results to the node that is aggregating the result rows.Both ...