您可以使用 Visual Explain 來要求新的計劃。 有時,當查詢仍在執行時,系統會要求您調整查詢的效能。 例如,查詢可能需要很長時間才能完成。 在 Visual Explain 中檢視計劃之後,您決定建立建議的索引,以提高查詢的速度。 因此,您建立索引,然後想要向資料庫最佳化工具發出信號,以根據新的索引來考量新的計劃。 以下是...
.0.02 rows=2 width=11) (2 rows)Examples Note For these examples, the sample output might vary depending on Amazon Redshift configuration.The following example returns the query plan for a query that selects the EVENTID, EVENTNAME, VENUEID, and VENUENAME from the EVENT and VENUE tables:...
Examples of parallel queries Assumptions OPTIMIZER_MODE = CHOOSE DEPT is small compared to EMP DEPT has an index (DEPT_INDX) on deptno column Three examples are presented Query #1: Serial Query #2: Parallel Query #3: Parallel, with forced optimization to RULE and forced usage of DEPT_INDX ...
This join typeis like ref, but with the addition that MySQL does an extra search for rowsthat contain NULL values. This join type optimization is used most often inresolving subqueries. In the following examples, MySQL can use a ref_or_nulljoin to process ref_table: SELECT * FROM ref_tab...
As a result, the query performance is poor. Keys such as the join key or group by key that are involved in expressions: If you use a CAST function to convert data types, the local join feature is not used. In this case, redistribution occurs. Examples: Example 1: Join two tables....
Examples To run the examples, initialize a demo cluster with the MovR workload. Start theMovR databaseon a 3-node CockroachDB demo cluster with a larger data set. cockroach demo movr--num-histories250000--num-promo-codes250000--num-rides125000--num-users12500--num-vehicles3750--nodes3 ...
CREATEINDEXidx_value_3ONkvstore(valueASC)INCLUDE(key); If you run the same query, you should see the following output: 1# EXPLAIN (ANALYZE, DIST, COSTS OFF) SELECT * FROM kvstore WHERE value LIKE 'ca%' ORDER BY VALUE;2QUERY PLAN3---4Index Only Scan using idx_value_3 on kvstore (a...
SELECT lpad(' ',level-1)||operation||' '||options||' '||object_name "Plan"FROM plan_tableCONNECT BY prior id = parent_idAND prior statement_id = statement_idSTART WITH id = 0 AND statement_id = '&1'ORDER BY id; EXPLAIN PLAN Examples ...
These examples may combine the output structures of MongoDB's classic and slot-based execution engines. They are not meant to be representative. Your output may differ significantly. explain.queryPlanner Contains information on the selection of the query plan by thequery optimizer. ...
A secure enclave is a secured region of memory within the SQL Server process that acts as a trusted execution environment for processing encrypted data. This enclave appears as a black box to SQL Server, and it isn't possible to view any data or code, even with a debugger....