Mysql explain ref func

MySQL resolves all joins using a nested-loop join method. This means that MySQL reads a row from the first table, and then finds a matching row in the second table, the third table, and so on. The EXPLAIN statement provides information about how MySQL executes statements.

EXPLAIN returns a row of information for each table used in the SELECT statement. It lists the tables in the output in the order that MySQL would read them while processing the statement. Now in the EXPLAIN plan in the ref there is the value as func.

I want to understand what exactly func in this case means and some details regarding this value. What is meaning of func in ref column of EXPLAIN plan. Also, since you are using OS X 10. Perhaps the data types on that OS have different qualities than 10. Seems like people are having compatibility problems with snow leopard.

Try installing MySQL 5. However, if the Query_result is unsuitable for explanation (need_ explain _interceptor() returns true), wrap the Query _result inside an Query_result_ explain object. Item_ func _sign Class Reference final. Convert get_time() from time to date in MYSQL _TIME. MySQL was able to use PRIMARY key as the index.

Let’s take a look at one more example query. Here we’ll basically take the union of two tables, products and productvariants, each joined with productline. Database tool that is tailored to suit specific needs of SQL developers.

This SQL query can be written in three different ways. Now imagine another table C with columns (i text) in which id an index but a non UNIQUE one. Table C has the following data: John! Imagine ref as JOIN between A and C: select A. This join type optimization is used most often in resolving subqueries.

IS NULL Optimization”. Why is a given query slow, what does the execution plan look like, how will JOINs be processe is the query using the correct indexes, or is it creating a temporary table? In this blog post, we’ll look at the EXPLAIN command and see how it can help us answer these questions. I have added the indexes however the sql query still slow and the type is ALL when EXPLAIN in the mysql.

I have also include the EXPLAIN and TABLE schema and indexes. Anyone have any ideas or suggestions are much appreciated. REGID` AS `REGID`,`r`. PHP MySQLi Introduction.

The MySQLi functions allows you to access MySQL database servers. Definition and Usage. The LOCATE() function returns the position of the first occurrence of a substring in a string.

If the substring is not found within the original string, this function returns 0. This function performs a case-insensitive search. There is one line which has an ALL type, however the table is marked as derived and many of the columns are NULL in the EXPLAIN output? How can I relate this back to what part of the query?