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SQL Development
Optimizing Query Performance : Inspecting what the optimizer produces : The _Sql_Qplan virtual system table
 

The _Sql_Qplan virtual system table

The virtual system table (VST) called _Sql_Qplan contains query plans for the last 10 queries that were executed. The CREATE TABLE statement shows you its definition in the following example.
CREATE TABLE "_Sql_Qplan" (
"_Pnumber" INTEGER NOT NULL,
"_Ptype" INTEGER NOT NULL,
"_Dtype" INTEGER NOT NULL,
"_Description" VARCHAR (255) NOT NULL,
"_Dseq" INTEGER NOT NULL
);
The following table offers a description for the columns in the _SQL_Qplan Virtual System Table.
Table 23. _SQL_Qplan Virtual System Table
Name
Description
_Pnumber
Query plan number, in descending order. Has no inherent significance. It merely groups together all the rows for a query plan.
_Ptype
Query plan type. Is > 0 for an application query and < 0 for an internally generated query.
_DType
Not used. In the future, this column will provide descriptive information about the plan.
_Description
Contains a description of part of the query plan.
_Dseq
Query plan row number, ordering the rows describing the plan for a particular table.