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...
you can usually find a row in one disk seek (because the index is probablycached). For bigger tables, you can estimate that, using B-tree indexes, youneed this many seeks to find a row: log(row_count) / log(index_block_length / 3* 2 / (index_length +data_pointer_length))...
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This tutorial describes how to use Explain reports to locate and fix problematic (slow) queries. It uses the DBT-3 database and begins with the following simple query example. SELECT * FROM orders WHERE YEAR(o_orderdate) = 1992 AND MONTH(o_orderdate) = 4 AND o_clerk LIKE '%0223';As...
Gets a detailed string representation explaining the AST of this type (with all specifiers and nested constructs such as pointers). This is intended to help debug queries and is a very expensive operation; not to be used in production queries. An example output is “const {pointer to {const...
pointer to a `sync.Mutex`. Both `WithGroup` and `WithAttrs` copy the handler. Both copies point to the same mutex. If the copy and the original used different mutexes and were used concurrently, then their output could be interleaved, or some output could be lost. Code like this: l2 ...
Let's start with a simple example:data Status = Green | Yellow | RedThis declares a data type Status which has exactly three different instances. For each instance a data constructor is defined that allows to create a new instance of the data type....
For example, select_type is DELETE for DELETE statements. table (JSON name: table_name) The name of the table to which the row of output refers. This can also be one of the following values: <unionM,N>: The row refers to the union of the rows with id values of M and N. ...
C# will not let me use a pointer and the code it not with with out one C# - change windows color scheme C# - How do you send message from server to clients C# - 'Using' & 'SQLConn', Does the connection close itself when falling out of scope? C# - Access to private method fro...
In fact, it's not a bug that occurs only in debug builds. In release-builds, `explain format=tree for conn` at sync point BEFORE_RESET_QUERY_PLAN gives incorrect query plan. Take the same query in the test case as an example, the correct plan (from explain <query>) is: ``` ->...