EXPLAIN doesn't reveal the RLS predicate that applies to dim_tbl. Amazon Redshift also logs the same node type to the STL_EXPLAIN system table. If a query contains a table that is subject to row-level security (RLS) policies, EXPLAIN displays a special RLS SecureScan node. Sends results back to the leader for further processing. Canīroadcast is also an attribute of Join Explain operatorsĭistribute rows to compute nodes for parallel processing Run scalar functions that don't involve any tableĮliminates duplicates from SELECT DISTINCT and UNIONĬompute aggregate and ranking window functions. Used to rearrange columns and compute expressions, that Used to parse textual input data during a load. Materialize rows for input to nested loop joins and some (The inner table is the table that is checkedįor matches and, in a join of two tables, is usually the smaller of the The Hash operator creates the hash tableįor the inner table of a join. Used for inner joins and left and right outer joins Can operate from disk based on virtue of "save". On virtue of fact that input hash can be disk-based.Īppend used with Subquery Scan to implement UNION and Virtue of fact that input hash can be disk-based. Intermediate sorted results derived from operations performed in parallel. Produces final sorted results of a query based on Sort performs the sorting specified by the ORDER BYĬlause as well as other operations such as UNIONs and joins. SORT: Operators and steps used when queries have to sort or If the Amazon Redshift configuration setting for force_hash_grouping setting is Operator sometimes chosen for grouped aggregate queries Operate from disk by virtue of hash table spilling to disk. Operator/step for grouped aggregate functions. Operator/step for scalar aggregate functions. Involve aggregate functions and GROUP BY operations. Typically the fastest Amazon Redshift join algorithm, not including otherĪGGREGATION: Operators and steps used for queries that (for join tables that are both distributed and sorted on the joiningĬolumns). (Inner input of hjoin is hash step which can beĪlso used for inner joins and outer joins Table, hashes the joining column, and finds matches in the inner hash table. (Cartesian products without a join condition) and some inequality joins.Īlso used for inner joins and left and right outer joinsĪnd typically faster than a nested loop join. Least optimal join mainly used for cross-joins Scan - Subquery scan and append are used to run UNION queries. Required for the join, and specific attributes of the query itself. Physical design of the tables being joined, the location of the data JOINS: Amazon Redshift uses different join operators based on the To run INSERT, UPDATE, and DELETE statements. Scans whole table sequentially from beginning to end also evaluates queryĬonstraints for every row (Filter) if specified with WHERE clause. Amazon Redshift relation scan or table scan operator or step.
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