MySQL Infusion UDF
Description
The MySQL Infusion UDF is a functionality enhancement for MySQL. It provides a varity of new string, math and aggregate functions.
Installation
In order to install the UDF, you need the MySQL header files installed on your machine. Additionally, you need GNU AWK (gawk). There is a very stupid Makefile with hard-coded paths, open the Makefile and adjust the things that are different to you. After that, all you need to do is:
git clone https://github.com/infusion/udf_infusion.git
cd udf_infusion
make
If anything went okay, you can now use all of the following functions.
Aggregate Functions
Get the median of a set
double median(double n);
mysql> SELECT median(weight) from t1;
Calculate the co-variance of two random variables
double covariance(double x, double y);
mysql> SELECT covariance(a, b) from t1;
Get the first element of a group
string group_first(string s);
mysql> SELECT group_first(s) from t1;
Get the last element of a group
string group_last(string s);
mysql> SELECT group_last(s) from t1;
Get the maximum number of elements less than a certain partial sum
int lesspart(double m, double psum);
mysql> SELECT lesspart(m, 1000) from t1;
Get the maximum number of elements less than a certain percentage of the partial sum
int lesspartpct(double m, double pct);
mysql> SELECT lesspartpct(m, 0.4) from t1;
Get the maximum number of elements less than average
int lessavg(double m);
mysql> SELECT lessavg(double m) from t1;
Calculates the 3th statistical moment of a data set: skewness See: http://geography.uoregon.edu/geogr/topics/moments.htm
double skewness(double m);
mysql> SELECT skewness(double m) from t1;
Calculates the 4th statistical moment of a data set: kurtosis See: http://geography.uoregon.edu/geogr/topics/moments.htm
double kurtosis(double m);
mysql> SELECT kurtosis(double m) from t1;
Misc Functions
Implementation of the famous ROW_NUMBER (http://msdn.microsoft.com/en-us/library/ms186734.aspx) function, which was previously only possible in MySQL with an ugly variable handling.
int row_number();
mysql> SELECT row_number() FROM t1;
### Determine how many rows are equal to an auto_increment column
mysql> SELECT count(id = row_number() or null) FROM t1;
A running SUM() for int and double/real values. Same as @x:= @x + value, but much faster and cleaner to code. The names are built up of R(unning)-SUM-(Int|Double)
int rsumi(int col);
double rsumd(double col);
mysql> SELECT rsumi(int_col) FROM t1;
mysql> SELECT rsumd(double_col) FROM t1;
A 64 bit hash function for MySQL, implementing a FNV algorithm
int fnv(string str);
mysql> SELECT cast( fnv( str ) as unsigned ) from t1;
Unfortunately, the UDF API doesn't support unsigned int return values. If you don't like the cast approach above, just add a stored function on your own:
CREATE FUNCTION ufnv(str TEXT) RETURNS INT UNSIGNED
RETURN cast( fnv( str ) as unsigned );
String Functions
Cuts a string if it's longer then a max value and appends "...". Words are not chopped.
string cut(string str, int num[, string x='...']);
mysql> SELECT cut('This is the funny world of MySQL...', 15);
+------------------------------------------------+
| cut('This is the funny world of MySQL...', 15) |
+------------------------------------------------+
| This is the... |
+------------------------------------------------+
1 row in set (0.00 sec)
The old name of this function was makeurl but I renamed it to slug, because this seems to be the more official term for this one. The Wordpress Codex says this: A slug is a few words that describe a post or a page. Slugs are usually a URL friendly version of the post title [...], but a slug can be anything you like. Slugs are meant to be used with permalinks as they help describe what the content at the URL is.
string slug(string str);
mysql> SELECT slug('Max Müller Straße!');
+----------------------------+
| slug('Max Müller Straße!') |
+----------------------------+
| max-mueller-strasse |
+----------------------------+
1 row in set (0.00 sec)
Generates a list of ngrams from a given string.
string ngram(string str[, int size=2]);
mysql> SELECT ngram('Lorem ipsum dolor');
+-------------------------------------------------------+
| ngram('Lorem ipsum dolor') |
+-------------------------------------------------------+
| _l lo or re em m_ _i ip ps su um m_ _d do ol lo or r_ |
+-------------------------------------------------------+
1 row in set (0.01 sec)
Math Functions
Round to the next multiple of a base.
int bround(int num, int base);
mysql> SELECT bround(13, 3);
+---------------+
| bround(13, 3) |
+---------------+
| 15 |
+---------------+
1 row in set (0.00 sec)
Round to the next power of 10. This breaks down 10^ceil(log(n) / log(10))
int xround(int num);
mysql> SELECT xround(55);
+------------+
| xround(55) |
+------------+
| 100 |
+------------+
1 row in set (0.00 sec)
Limits a number to a specified lower min- and/or a upper max value. Not used min/max can be ignored with NULL
double bound(double num, double min, double max);
mysql> SELECT bound(12, 0, 4);
+-----------------+
| bound(12, 0, 4) |
+-----------------+
| 4.00000000 |
+-----------------+
1 row in set (0.00 sec)
Calculates N over K
int noverk(int n, int k);
mysql> select noverk(49, 6);
+---------------+
| noverk(49, 6) |
+---------------+
| 13983816 |
+---------------+
1 row in set (0.00 sec)
Binary Functions
Check if a bit-flag is set in the number.
bool isbit(int mask, int n);
mysql> SELECT isbit(5, 2);
+-------------+
| isbit(5, 2) |
+-------------+
| 1 |
+-------------+
1 row in set (0.00 sec)
Set a bit-flag at the position to 1 (or optionally 0).
int setbit(int mask, int n[, bool init=1]);
mysql> SELECT setbit(8, 4, 1);
+-----------------+
| setbit(8, 4, 1) |
+-----------------+
| 24 |
+-----------------+
1 row in set (0.00 sec)
Toggle/invert a bit-flag at the given position.
int invbit(int mask, int n);
mysql> SELECT invbit(8, 2);
+--------------+
| invbit(8, 2) |
+--------------+
| 12 |
+--------------+
1 row in set (0.00 sec)
Rotate the bits within the number
int rotbit(int mask, int n);
mysql> select rotbit(13, 1);
+---------------+
| rotbit(13, 1) |
+---------------+
| 26 |
+---------------+
1 row in set (0.00 sec)
Get a smaller integer from a bigger integer. See: http://www.xarg.org/2009/12/store-small-numbers-in-big-numbers/
int getint(int mask, int x, int y);
mysql> SELECT GETINT(4283942, 4, 8);
+-----------------------+
| getint(4283942, 4, 8) |
+-----------------------+
| 2 |
+-----------------------+
1 row in set (0.00 sec)
Set a smaller integer into a bigger integer. See: http://www.xarg.org/2009/12/store-small-numbers-in-big-numbers/
int setint(int mask, int x, int y, int m);
mysql> SELECT SETINT(4283942, 4, 8, 10);
+---------------------------+
| setint(4283942, 4, 8, 10) |
+---------------------------+
| 4284070 |
+---------------------------+
1 row in set (0.00 sec)
License
Licensed under GPL Version 2 license.