mysql - My JOIN query on multiple tables is very slow -

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my current query advanced search takes 60 secs complete. suggestions improving this? database: mysql webserver: apache - php (pdo)

current code structure:

select  b.title, count(*) num  library.physicalinfo  left join library.bibliographicinfo b      on a.bookid = b.bibliographicinfoid  left join library.authors c      on b.bibliographicinfoid = c.bookid  left join library.bookauthors d      on c.bookauthorid = d.personid  left join library.series e      on b.bibliographicinfoid = e.bookid  left join library.bookslocation f      on a.location = f.booklocationid  left join library.publishstatement g      on b.bibliographicinfoid=g.bookid  left join library.publisher h      on g.publisherid = h.publisherid  (     b.title  '%سلام%' or              d.name '%سلام%' or              f.location '%سلام%' or              g.place  '%سلام%' or              g.year '%سلام%' or              h.name '%سلام%' )  limit 0, 30

i've created indexes fields used in join comparisons , where statements:

create index personid on library.bookauthors(personid); ....

my table structures are:

mysql> describe physicalinfo;  +----------------+--------------+------+-----+---------+----------------+ | field          | type         | null | key | default |          | +----------------+--------------+------+-----+---------+----------------+ | physicalinfoid | int(11)      | no   | pri | null    | auto_increment | | volume         | varchar(10)  | yes  |     | null    |                | | section        | varchar(100) | yes  |     | null    |                | | year           | varchar(10)  | yes  |     | null    |                | | registerno     | varchar(20)  | yes  |     | null    |                | | barcode        | varchar(45)  | yes  | mul | null    |                | | location       | int(11)      | yes  | mul | null    |                | | bookid         | int(11)      | yes  | mul | null    |                | | version        | varchar(10)  | yes  |     | null    |                | +----------------+--------------+------+-----+---------+----------------+  mysql> describe bibliographicinfo;  +------------------------+---------------+------+-----+---------+----------------+ | field                  | type          | null | key | default | | +------------------------+---------------+------+-----+---------+----------------+ | bibliographicinfoid    | int(11)       | no   | pri | null    | auto_increment | | lcno                   | varchar(45)   | yes  |     | null    | | | devino                 | varchar(45)   | yes  |     | null    | | | title                  | varchar(200)  | yes  | mul | null    | | | isbn                   | varchar(20)   | yes  | mul | null    | | | language               | int(11)       | yes  |     | null    | | | isreference            | smallint(6)   | yes  |     | null    | | +------------------------+---------------+------+-----+---------+----------------+

explain extended result:

*************************** 1. row ***************************            id: 1   select_type: simple         table:          type: possible_keys: null           key: null       key_len: null           ref: null          rows: 348390      filtered: 100.00         extra: null *************************** 2. row ***************************            id: 1   select_type: simple         table: b          type: eq_ref possible_keys: primary,bibliographicinfoid           key: primary       key_len: 4           ref: library.a.bookid          rows: 1      filtered: 100.00         extra: null *************************** 3. row ***************************            id: 1   select_type: simple         table: c          type: ref possible_keys: bookid_idx,bookid           key: bookid_idx       key_len: 5           ref: library.b.bibliographicinfoid          rows: 1      filtered: 100.00         extra: null *************************** 4. row ***************************            id: 1   select_type: simple         table: d          type: eq_ref possible_keys: primary,personid           key: primary       key_len: 4           ref: library.c.bookauthorid          rows: 1      filtered: 100.00         extra: null *************************** 5. row ***************************            id: 1   select_type: simple         table: e          type: ref possible_keys: bookid           key: bookid       key_len: 5           ref: library.b.bibliographicinfoid          rows: 2      filtered: 100.00         extra: using index *************************** 6. row ***************************            id: 1   select_type: simple         table: f          type: eq_ref possible_keys: primary,booklocationid           key: primary       key_len: 4           ref: library.a.location          rows: 1      filtered: 100.00         extra: null *************************** 7. row ***************************            id: 1   select_type: simple         table: g          type: ref possible_keys: book_idx,bookid           key: book_idx       key_len: 5           ref: library.b.bibliographicinfoid          rows: 1      filtered: 100.00         extra: null *************************** 8. row ***************************            id: 1   select_type: simple         table: h          type: eq_ref possible_keys: primary,publisherid           key: primary       key_len: 4           ref: library.g.publisherid          rows: 1      filtered: 100.00         extra: using 8 rows in set, 1 warning (0.00 sec)

my current query (on 5million records) takes 60 secs! question is:

  1. what doing wrong here?
  2. why first row in explain extended has type=all? far know, worst type , shouldn't there because i've created indexes bookid , primary key of table.

  • the first thing think indexes. if choose them wisely can improve performance significantly. see here.
  • sometimes should consider flattening tables. way break relational database rules of normalization gain speed performing less "joins".
  • yet way use: if 1 of table hasn't many values, can in separate query, moving "join" field key, (caching array) , perform join after query execution when fetching records in php(or other language) code
  • and approach perform job on time basis prepare data , insert table, ready fetching(not possible in many use cases due delay)

and can store values in cache.


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