Example EXPLAIN outputThe XML result of the EXPLAIN command with row numbers turned on is:XML Kopiera 1 \<?xml version="1.0" encoding="utf-8"?> 2 <dsql_query> 3 <sql>SELECT CAST (AVG(YearlyIncome) AS int) AS AverageIncome, 4 CAST(AVG(FIS.SalesAmount) AS int) AS AverageSales,...
Also note that the numbers, and even the selected query strategy, might vary betweenPostgreSQLreleases due to planner improvements. In addition, the ANALYZE command uses random sampling to estimate data statistics; therefore, it is possible for cost estimates to change after a fresh run of ANALYZE...
* Put an appropriate separator between multiple plans */voidExplainSeparatePlans(ExplainState *es){ switch (es->format) { case EXPLAIN_FORMAT_TEXT: /* add a blank line */ appendStringInfoChar(es->str, '\n'); break; case EXPLAIN_FORMAT_XML: case EXPLAIN_FORMAT_JSON: case EXPLAIN_FORMAT...
With the help ofEXPLAIN, you can see where you should add indexes to tables so that thestatement executes faster by using indexes to find rows. You can also useEXPLAIN to check whether the optimizer joins the tables in an optimal order. Togive a hint to the optimizer to use a join orde...
WhenEXPLAINis used withFOR CONNECTIONconnection_idrather than an explainable statement, it displays the execution plan for the statement executing in the named connection. SeeSection 8.8.4, “Obtaining Execution Plan Information for a Named Connection”. ...
The dependencies between the different stages of the plan The description of each of the stages The description of the stages itself shows a sequence of operators with the metadata associated with the operators. The metadata may comprise of things like filter expressions for the FilterOperator or ...
Figure 19: Example plan output using SORT MERGE JOIN Beginning with Oracle Database 12c Release 2, band joins available. They make certain merge joins more efficient where there are BETWEEN predicates. 14 THE ORACLE OPTIMIZER EXPLAIN THE EXPLAIN PLAN Cartesian join - The optimizer joins every row...
For an example of an explanation that’s too complicated, takeStar Trek: Insurrection. In this film, the peaceful Ba’ku live in one village on a hidden planet with radiation that acts as a fountain of youth. The villainous Son’a want to harvest this radiation for themselves, but doing ...
Describe an externality associated with health. It can be either positive or negative. Describe the advantage of using a pollution tax (or Marketable Pollution Permits) rather than a command-and-control system to internalize an externality.
An inflation rate is termed as the rate of change in the general financial value of the products and services. The lower inflation rate would lead to reduce the market price level. With an increase in the real income of the consumer, the aggregate demand would increase....