SphinxSE is a MySQL storage engine that can be compiled into MySQL/MariaDB servers using their pluggable architecture.

Despite its name, SphinxSE does not actually store any data itself. Instead, it serves as a built-in client that enables the MySQL server to communicate with searchd, execute search queries, and retrieve search results. All indexing and searching take place outside MySQL.

Some common SphinxSE applications include:

• Simplifying the porting of MySQL Full-Text Search (FTS) applications to Manticore;
• Enabling Manticore use with programming languages for which native APIs are not yet available;
• Offering optimizations when additional Manticore result set processing is needed on the MySQL side (e.g., JOINs with original document tables or additional MySQL-side filtering).

You will need to obtain a copy of MySQL sources, prepare those, and then recompile MySQL binary. MySQL sources (mysql-5.x.yy.tar.gz) could be obtained from http://dev.mysql.com website.

1. copy sphinx.5.0.yy.diff patch file into MySQL sources directory and run

   $ patch -p1 < sphinx.5.0.yy.diff

   If there's no .diff file exactly for the specific version you need to: build, try applying .diff with closest version numbers. It is important that the patch should apply with no rejects.

2. in MySQL sources directory, run

   $ sh BUILD/autorun.sh

3. in MySQL sources directory, create sql/sphinx directory in and copy all files in mysqlse directory from Manticore sources there. Example:

   $ cp -R /root/builds/sphinx-0.9.7/mysqlse /root/builds/mysql-5.0.24/sql/sphinx

4. configure MySQL and enable the new engine:

   $ ./configure --with-sphinx-storage-engine

5. build and install MySQL:

   $ make
   $ make install

1. In the MySQL sources directory, create a storage/sphinx directory and copy all files from the mysqlse directory in the Manticore sources to this new location. For example:

   $ cp -R /root/builds/sphinx-0.9.7/mysqlse /root/builds/mysql-5.1.14/storage/sphinx

2. In the MySQL source directory, run:

   $ sh BUILD/autorun.sh

3. Configure MySQL and enable the Manticore engine:

   $ ./configure --with-plugins=sphinx

4. Build and install MySQL:

   $ make
   $ make install

mysql> show engines;

+------------+----------+-------------------------------------------------------------+
| Engine     | Support  | Comment                                                     |
+------------+----------+-------------------------------------------------------------+
| MyISAM     | DEFAULT  | Default engine as of MySQL 3.23 with great performance      |
  ...
| SPHINX     | YES      | Manticore storage engine                                       |
  ...
+------------+----------+-------------------------------------------------------------+
13 rows in set (0.00 sec)

To search using SphinxSE, you'll need to create a special ENGINE=SPHINX "search table" and then use a SELECT statement with the full-text query placed in the WHERE clause for the query column.

Here's an example create statement and search query:

CREATE TABLE t1
(
    id          INTEGER UNSIGNED NOT NULL,
    weight      INTEGER NOT NULL,
    query       VARCHAR(3072) NOT NULL,
    group_id    INTEGER,
    INDEX(query)
) ENGINE=SPHINX CONNECTION="sphinx://localhost:9312/test";

SELECT * FROM t1 WHERE query='test it;mode=any';

In a search table, the first three columns must have the following types: INTEGER UNSIGNED or BIGINT for the 1st column (document ID), INTEGER or BIGINT for the 2nd column (match weight), and VARCHAR or TEXT for the 3rd column (your query). This mapping is fixed; you cannot omit any of these three required columns, move them around, or change their types. Additionally, the query column must be indexed, while all others should remain unindexed. Column names are ignored, so you can use any arbitrary names.

Additional columns must be either INTEGER, TIMESTAMP, BIGINT, VARCHAR, or FLOAT. They will be bound to attributes provided in the Manticore result set by name, so their names must match the attribute names specified in sphinx.conf. If there's no matching attribute name in the Manticore search results, the column will have NULL values.

Special "virtual" attribute names can also be bound to SphinxSE columns. Use _sph_ instead of @ for that purpose. For example, to obtain the values of @groupby, @count, or @distinct virtual attributes, use _sph_groupby, _sph_count, or _sph_distinct column names, respectively.

The CONNECTION string parameter is used to specify the Manticore host, port, and table. If no connection string is specified in CREATE TABLE, the table name * (i.e., search all tables) and localhost:9312 are assumed. The connection string syntax is as follows:

CONNECTION="sphinx://HOST:PORT/TABLENAME"

You can change the default connection string later:

mysql> ALTER TABLE t1 CONNECTION="sphinx://NEWHOST:NEWPORT/NEWTABLENAME";

You can also override these parameters on a per-query basis.

As shown in the example, both the query text and search options should be placed in the WHERE clause on the search query column (i.e., the 3rd column). Options are separated by semicolons and their names from values by an equality sign. Any number of options can be specified. The available options are:

• query - query text;
• mode - matching mode. Must be one of "all", "any", "phrase", "boolean", or "extended". Default is "all";
• sort - match sorting mode. Must be one of "relevance", "attr_desc", "attr_asc", "time_segments", or "extended". In all modes besides "relevance", the attribute name (or sorting clause for "extended") is also required after a colon:

  ... WHERE query='test;sort=attr_asc:group_id';
  ... WHERE query='test;sort=extended:@weight desc, group_id asc';

• offset - offset into the result set; default is 0;
• limit - number of matches to retrieve from the result set; default is 20;
• index - names of the tables to search:

  ... WHERE query='test;index=test1;';
  ... WHERE query='test;index=test1,test2,test3;';

• minid, maxid - min and max document ID to match;
• weights - comma-separated list of weights to be assigned to Manticore full-text fields:

  ... WHERE query='test;weights=1,2,3;';

• filter, !filter - comma-separated attribute name and a set of values to match:

  # only include groups 1, 5 and 19
  ... WHERE query='test;filter=group_id,1,5,19;';
  # exclude groups 3 and 11
  ... WHERE query='test;!filter=group_id,3,11;';

• range, !range - comma-separated (integer or bigint) Manticore attribute name, and min and max values to match:

  # include groups from 3 to 7, inclusive
  ... WHERE query='test;range=group_id,3,7;';
  # exclude groups from 5 to 25
  ... WHERE query='test;!range=group_id,5,25;';

• floatrange, !floatrange - comma-separated (floating point) Manticore attribute name, and min and max values to match:

  # filter by a float size
  ... WHERE query='test;floatrange=size,2,3;';
  # pick all results within 1000 meter from geoanchor
  ... WHERE query='test;floatrange=@geodist,0,1000;';

• maxmatches - maxmatches - per-query max matches value, as in max_matches search option:

  ... WHERE query='test;maxmatches=2000;';

• cutoff - maximum allowed matches, as in cutoff search option:

  ... WHERE query='test;cutoff=10000;';

• maxquerytime - maximum allowed query time (in milliseconds), as in max_query_time search option:

  ... WHERE query='test;maxquerytime=1000;';

• groupby - group-by function and attribute. Read this about grouping search results:

  ... WHERE query='test;groupby=day:published_ts;';
  ... WHERE query='test;groupby=attr:group_id;';

• groupsort - group-by sorting clause:

  ... WHERE query='test;groupsort=@count desc;';

• distinct - an attribute to compute COUNT(DISTINCT) for when doing group-by:

  ... WHERE query='test;groupby=attr:country_id;distinct=site_id';

• indexweights - comma-separated list of table names and weights to use when searching through several tables:

  ... WHERE query='test;indexweights=tbl_exact,2,tbl_stemmed,1;';

• fieldweights - comma-separated list of per-field weights that can be used by the ranker:

  ... WHERE query='test;fieldweights=title,10,abstract,3,content,1;';

• comment - a string to mark this query in query log, as in comment search option:

  ... WHERE query='test;comment=marker001;';

• select - a string with expressions to compute:

  ... WHERE query='test;select=2*a+3*** as myexpr;';

• host, port - remote searchd host name and TCP port, respectively:

  ... WHERE query='test;host=sphinx-test.loc;port=7312;';

• ranker - a ranking function to use with "extended" matching mode, as in ranker. Known values are "proximity_bm25", "bm25", "none", "wordcount", "proximity", "matchany", "fieldmask", "sph04", "expr:EXPRESSION" syntax to support expression-based ranker (where EXPRESSION should be replaced with your specific ranking formula), and "export:EXPRESSION":

  ... WHERE query='test;mode=extended;ranker=bm25;';
  ... WHERE query='test;mode=extended;ranker=expr:sum(lcs);';

  The "export" ranker functions similarly to ranker=expr, but it retains the per-document factor values, while ranker=expr discards them after computing the final WEIGHT() value. Keep in mind that ranker=export is intended for occasional use, such as training a machine learning (ML) function or manually defining your own ranking function, and should not be used in actual production. When utilizing this ranker, you'll likely want to examine the output of the RANKFACTORS() function, which generates a string containing all the field-level factors for each document.

SELECT *, WEIGHT(), RANKFACTORS()
    FROM myindex
    WHERE MATCH('dog')
    OPTION ranker=export('100*bm25');

*************************** 1\. row ***************************
           id: 555617
    published: 1110067331
   channel_id: 1059819
        title: 7
      content: 428
     weight(): 69900
rankfactors(): bm25=699, bm25a=0.666478, field_mask=2,
doc_word_count=1, field1=(lcs=1, hit_count=4, word_count=1,
tf_idf=1.038127, min_idf=0.259532, max_idf=0.259532, sum_idf=0.259532,
min_hit_pos=120, min_best_span_pos=120, exact_hit=0,
max_window_hits=1), word1=(tf=4, idf=0.259532)
*************************** 2\. row ***************************
           id: 555313
    published: 1108438365
   channel_id: 1058561
        title: 8
      content: 249
     weight(): 68500
rankfactors(): bm25=685, bm25a=0.675213, field_mask=3,
doc_word_count=1, field0=(lcs=1, hit_count=1, word_count=1,
tf_idf=0.259532, min_idf=0.259532, max_idf=0.259532, sum_idf=0.259532,
min_hit_pos=8, min_best_span_pos=8, exact_hit=0, max_window_hits=1),
field1=(lcs=1, hit_count=2, word_count=1, tf_idf=0.519063,
min_idf=0.259532, max_idf=0.259532, sum_idf=0.259532, min_hit_pos=36,
min_best_span_pos=36, exact_hit=0, max_window_hits=1), word1=(tf=3,
idf=0.259532)

• geoanchor - geodistance anchor. Learn more about Geo-search in this section. Takes 4 parameters, which are the latitude and longitude attribute names, and anchor point coordinates, respectively:

  ... WHERE query='test;geoanchor=latattr,lonattr,0.123,0.456';

One very important note is that it is much more efficient to let Manticore handle sorting, filtering, and slicing the result set, rather than increasing the max matches count and using WHERE, ORDER BY, and LIMIT clauses on the MySQL side. This is due to two reasons. First, Manticore employs a variety of optimizations and performs these tasks better than MySQL. Second, less data would need to be packed by searchd, transferred, and unpacked by SphinxSE.

mysql> SHOW ENGINE SPHINX STATUS;

+--------+-------+-------------------------------------------------+
| Type   | Name  | Status                                          |
+--------+-------+-------------------------------------------------+
| SPHINX | stats | total: 25, total found: 25, time: 126, words: 2 |
| SPHINX | words | sphinx:591:1256 soft:11076:15945                |
+--------+-------+-------------------------------------------------+
2 rows in set (0.00 sec)

mysql> SHOW STATUS LIKE 'sphinx_%';

+--------------------+----------------------------------+
| Variable_name      | Value                            |
+--------------------+----------------------------------+
| sphinx_total       | 25                               |
| sphinx_total_found | 25                               |
| sphinx_time        | 126                              |
| sphinx_word_count  | 2                                |
| sphinx_words       | sphinx:591:1256 soft:11076:15945 |
+--------------------+----------------------------------+
5 rows in set (0.00 sec)

mysql> SELECT content, date_added FROM test.documents docs
-> JOIN t1 ON (docs.id=t1.id)
-> WHERE query="one document;mode=any";

mysql> SHOW ENGINE SPHINX STATUS;

+-------------------------------------+---------------------+
| content                             | docdate             |
+-------------------------------------+---------------------+
| this is my test document number two | 2006-06-17 14:04:28 |
| this is my test document number one | 2006-06-17 14:04:28 |
+-------------------------------------+---------------------+
2 rows in set (0.00 sec)

+--------+-------+---------------------------------------------+
| Type   | Name  | Status                                      |
+--------+-------+---------------------------------------------+
| SPHINX | stats | total: 2, total found: 2, time: 0, words: 2 |
| SPHINX | words | one:1:2 document:2:2                        |
+--------+-------+---------------------------------------------+
2 rows in set (0.00 sec)

SphinxSE also features a UDF function that allows you to create snippets using MySQL. This functionality is similar to HIGHLIGHT(), but can be accessed through MySQL+SphinxSE.

The binary providing the UDF is called sphinx.so and should be automatically built and installed in the appropriate location along with SphinxSE. If it doesn't install automatically for some reason, locate sphinx.so in the build directory and copy it to your MySQL instance's plugins directory. Once done, register the UDF with the following statement:

CREATE FUNCTION sphinx_snippets RETURNS STRING SONAME 'sphinx.so';

The function name must be sphinx_snippets; you cannot use an arbitrary name. The function arguments are as follows:

Prototype: function sphinx_snippets ( document, table, words [, options] );

The document and words arguments can be either strings or table columns. Options must be specified like this: 'value' AS option_name. For a list of supported options, refer to the Highlighting section. The only UDF-specific additional option is called sphinx and allows you to specify the searchd location (host and port).

Usage examples:

SELECT sphinx_snippets('hello world doc', 'main', 'world',
    'sphinx://192.168.1.1/' AS sphinx, true AS exact_phrase,
    '[**]' AS before_match, '[/**]' AS after_match)
FROM documents;

SELECT title, sphinx_snippets(text, 'table', 'mysql php') AS text
    FROM sphinx, documents
    WHERE query='mysql php' AND sphinx.id=documents.id;

With the MySQL FEDERATED engine, you can connect to a local or remote Manticore instance from MySQL/MariaDB and perform search queries.

An actual Manticore query can't be used directly with the FEDERATED engine and must be "proxied" (sent as a string in a column) due to the FEDERATED engine's limitations and the fact that Manticore implements custom syntax like the MATCH clause.

To search via FEDERATED, you first need to create a FEDERATED engine table. The Manticore query will be included in a query column in the SELECT performed over the FEDERATED table.

CREATE TABLE t1
(
    id          INTEGER UNSIGNED NOT NULL,
    year        INTEGER NOT NULL,
    rating      FLOAT,
    query       VARCHAR(1024) NOT NULL,
    INDEX(query)
) ENGINE=FEDERATED
DEFAULT CHARSET=utf8
CONNECTION='mysql://FEDERATED@127.0.0.1:9306/DB/movies';

Query OK, 0 rows affected (0.00 sec)

SELECT * FROM t1 WHERE query='SELECT * FROM movies WHERE MATCH (\'pie\')';

+----+------+--------+------------------------------------------+
| id | year | rating | query                                    |
+----+------+--------+------------------------------------------+
|  1 | 2019 |      5 | SELECT * FROM movies WHERE MATCH ('pie') |
+----+------+--------+------------------------------------------+
1 row in set (0.04 sec)

The only fixed mapping is the query column. It is mandatory and must be the only column with a table attached.

The Manticore table linked via FEDERATED must be a physical table (plain or real-time).

The FEDERATED table should have columns with the same names as the remote Manticore table attributes since they will be bound to the attributes provided in the Manticore result set by name. However, it might map only some attributes, not all of them.

Manticore server identifies a query from a FEDERATED client by the user name "FEDERATED". The CONNECTION string parameter is used to specify the Manticore host, SQL port, and tables for queries coming through the connection. The connection string syntax is as follows:

CONNECTION="mysql://FEDERATED@HOST:PORT/DB/TABLENAME"

Since Manticore doesn't have the concept of a database, the DB string can be random as it will be ignored by Manticore, but MySQL requires a value in the CONNECTION string definition. As seen in the example, the full SELECT SQL query should be placed in a WHERE clause against the query column.

Only the SELECT statement is supported, not INSERT, REPLACE, UPDATE, or DELETE.

One very important note is that it is much more efficient to allow Manticore to perform sorting, filtering, and slicing the result set than to increase the max matches count and use WHERE, ORDER BY, and LIMIT clauses on the MySQL side. This is for two reasons. First, Manticore implements a number of optimizations and performs better than MySQL for these tasks. Second, less data needs to be packed by searchd, transferred, and unpacked between Manticore and MySQL.

SELECT t1.id, t1.year, comments.comment FROM t1 JOIN comments ON t1.id=comments.post_id WHERE query='SELECT * FROM movies WHERE MATCH (\'pie\')';

+----+------+--------------+
| id | year | comment      |
+----+------+--------------+
|  1 | 2019 | was not good |
+----+------+--------------+
1 row in set (0.00 sec)

Manticore can be extended with user-defined functions, or UDFs for short, like this:

SELECT id, attr1, myudf (attr2, attr3+attr4) ...

You can dynamically load and unload UDFs into searchd without having to restart the server, and use them in expressions when searching, ranking, etc. A quick summary of the UDF features is as follows:

• UDFs can take integer (both 32-bit and 64-bit), float, string, MVA, or PACKEDFACTORS() arguments.
• UDFs can return integer, float, or string values.
• UDFs can check the argument number, types, and names during the query setup phase, and raise errors.

We do not yet support aggregation functions. In other words, your UDFs will be called for just a single document at a time and are expected to return some value for that document. Writing a function that can compute an aggregate value like AVG() over the entire group of documents that share the same GROUP BY key is not yet possible. However, you can use UDFs within the built-in aggregate functions: that is, even though MYCUSTOMAVG() is not supported yet, AVG(MYCUSTOMFUNC()) should work just fine!

UDFs offer a wide range of applications, such as:

• incorporating custom mathematical or string functions;
• accessing databases or files from within Manticore;
• creating complex ranking functions.

Plugins offer additional opportunities to expand search functionality. They can currently be used to compute custom rankings and tokenize documents and queries.

Here's the complete list of plugin types:

• UDF plugins (essentially UDFs, but since they're plugged in, they're also referred to as 'UDF plugins')
• ranker plugins
• indexing-time token filter plugins
• query-time token filter plugins

This section covers the general process of writing and managing plugins; specifics related to creating different types of plugins are discussed in their respective subsections.

So, how do you write and use a plugin? Here's a quick four-step guide:

• create a dynamic library (either .so or .dll), most likely using C or C++;
• load the plugin into searchd with CREATE PLUGIN;
• use the plugin with plugin-specific calls (usually through specific OPTIONS).
• unload or reload a plugin with DROP PLUGIN and RELOAD PLUGINS, respectively.

Note that while UDFs are first-class plugins, they are installed using a separate CREATE FUNCTION statement. This allows for a neat specification of the return type, without sacrificing backward compatibility or changing the syntax.

Dynamic plugins are supported in threads and thread_pool workers. Multiple plugins (and/or UDFs) can be contained in a single library file. You may choose to either group all project-specific plugins in one large library or create a separate library for each UDF and plugin; it's up to you.

As with UDFs, you should include the src/sphinxudf.h header file. At the very least, you'll need the SPH_UDF_VERSION constant to implement an appropriate version function. Depending on the specific plugin type, you may or may not need to link your plugin with src/sphinxudf.c. However, all functions implemented in sphinxudf.c are related to unpacking the PACKEDFACTORS() blob, and no plugin types have access to that data. So currently, linking with just the header should suffice. (In fact, if you copy over the UDF version number, you won't even need the header file for some plugin types.)

Formally, plugins are simply sets of C functions that adhere to a specific naming pattern. You're typically required to define one key function for the primary task, but you can also define additional functions. For instance, to implement a ranker called "myrank", you must define a myrank_finalize() function that returns the rank value. However, you can also define myrank_init(), myrank_update(), and myrank_deinit() functions. Specific sets of well-known suffixes and call arguments differ based on the plugin type, but _init() and _deinit() are generic, and every plugin has them. Hint: for a quick reference on known suffixes and their argument types, refer to sphinxplugin.h, where the call prototypes are defined at the beginning of the file.

Even though the public interface is defined in pure C, our plugins essentially follow an object-oriented model. Indeed, every _init() function receives a void ** userdata out-parameter, and the pointer value stored at (*userdata) is then passed as the first argument to all other plugin functions. So you can think of a plugin as a class that gets instantiated every time an object of that class is needed to handle a request: the userdata pointer serves as the this pointer; the functions act as methods, and the _init() and _deinit() functions work as constructor and destructor, respectively.

This minor OOP-in-C complication arises because plugins run in a multi-threaded environment, and some need to maintain state. You can't store that state in a global variable in your plugin, so we pass around a userdata parameter, which naturally leads to the OOP model. If your plugin is simple and stateless, the interface allows you to omit _init(), _deinit(), and any other functions.

To summarize, here's the simplest complete ranker plugin in just three lines of C code:

// gcc -fPIC -shared -o myrank.so myrank.c
#include "sphinxudf.h"
int myrank_ver() { return SPH_UDF_VERSION; }
int myrank_finalize(void *u, int w) { return 123; }

Here's how to use the simple ranker plugin:

mysql> CREATE PLUGIN myrank TYPE 'ranker' SONAME 'myrank.dll';
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT id, weight() FROM test1 WHERE MATCH('test') OPTION ranker=myrank('');
+------+----------+
| id   | weight() |
+------+----------+
|    1 |      123 |
|    2 |      123 |
+------+----------+
2 rows in set (0.01 sec)