Documentation » History » Version 15
Álvaro Herrera, 12/20/2005 10:08 AM
Make the examples more consistent.
1 | 6 | Álvaro Herrera | = PL/php - PHP Procedural Language for PostgreSQL = |
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2 | 1 | bford - | |
3 | 4 | Álvaro Herrera | [[PageOutline(2-3,Contents,inline)]] |
4 | 1 | bford - | |
5 | 6 | Álvaro Herrera | == What is PL/php? == |
6 | 1 | bford - | |
7 | 6 | Álvaro Herrera | PL/php is a procedural language with hooks into the PostgreSQL |
8 | 8 | Álvaro Herrera | database sytem, intended to allow writing of PHP functions for |
9 | use as functions inside the PostgreSQL database. |
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10 | It was written by Command Prompt, Inc. and has since |
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11 | 1 | bford - | been open sourced and licensed under the PHP and PostgreSQL (BSD) |
12 | licenses. |
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13 | |||
14 | == Download and Installation == |
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15 | 3 | Álvaro Herrera | |
16 | 8 | Álvaro Herrera | Please see [wiki:InstallDocs10 the installation documentation] for instructions on |
17 | how to install PL/php 1.0. To install the new code, which only works with PostgreSQL |
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18 | 8.0 and 8.1 and is currently in development, see [wiki:InstallDocs this page instead]. |
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19 | 7 | Álvaro Herrera | |
20 | 1 | bford - | == Creating the PL/php language == |
21 | 7 | Álvaro Herrera | |
22 | 8 | Álvaro Herrera | Please see the documentation on [wiki:CreateLang80 how to create the language in a database] |
23 | once the library is installed. If you are using PostgreSQL 8.1 you must follow |
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24 | [wiki:CreateLang these other instructions] instead. |
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25 | 7 | Álvaro Herrera | |
26 | 2 | Álvaro Herrera | == Functions and Arguments == |
27 | 3 | Álvaro Herrera | |
28 | 1 | bford - | To create a function, use the standard syntax: |
29 | |||
30 | |||
31 | {{{ |
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32 | 6 | Álvaro Herrera | CREATE FUNCTION funcname (argument-types) RETURNS return-type AS $$ |
33 | 1 | bford - | # plphp function body here |
34 | 6 | Álvaro Herrera | $$ LANGUAGE 'plphp'; |
35 | 1 | bford - | }}} |
36 | |||
37 | |||
38 | Arguments are passed in the $args array and the result value is returned |
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39 | with the 'return' statement. |
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40 | |||
41 | 2 | Álvaro Herrera | |
42 | 1 | bford - | {{{ |
43 | 6 | Álvaro Herrera | CREATE FUNCTION plphp_max(integer, integer) RETURNS integer AS $$ |
44 | 1 | bford - | if ($args[0] > $args[1]) { |
45 | return $args[0]; |
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46 | } else { |
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47 | return $args[1]; |
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48 | } |
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49 | 6 | Álvaro Herrera | $$ STRICT LANGUAGE 'plphp' |
50 | 1 | bford - | }}} |
51 | |||
52 | 2 | Álvaro Herrera | |
53 | 1 | bford - | NOTE: The use of the STRICT clause saves us from having to |
54 | think about NULL input values to our function. If a NULL value is |
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55 | 2 | Álvaro Herrera | passed, the function will not be run at all, but will rather just |
56 | 1 | bford - | return a NULL result automatically. |
57 | |||
58 | In a non-strict function, if the actual value of an argument is NULL, |
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59 | the corresponding $args[n-1] variable will be set to an empty string |
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60 | (unset). |
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61 | |||
62 | |||
63 | == Data Types and Returns == |
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64 | |||
65 | 9 | Álvaro Herrera | The arguments passed into your PL/php function are converted to text |
66 | 3 | Álvaro Herrera | so you can manipulate them with the loose typing enjoyed in typical |
67 | 1 | bford - | PHP scripts. Conversely, the return command will accept any string |
68 | that is acceptable input format for the function's declared return |
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69 | type. |
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70 | |||
71 | |||
72 | 3 | Álvaro Herrera | == Global Shared Variable == |
73 | 1 | bford - | |
74 | There is a global variable that can be used to store data between |
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75 | function calls, called $_SHARED. |
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76 | |||
77 | {{{ |
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78 | 6 | Álvaro Herrera | CREATE FUNCTION set_var(text) RETURNS text AS $$ |
79 | 1 | bford - | global $_SHARED; |
80 | 6 | Álvaro Herrera | $_SHARED['first']=$args[0]; |
81 | return 'ok'; |
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82 | $$ LANGUAGE 'plphp'; |
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83 | 1 | bford - | |
84 | 6 | Álvaro Herrera | CREATE FUNCTION get_var() RETURNS text AS $$ |
85 | 1 | bford - | global $_SHARED; |
86 | 6 | Álvaro Herrera | return $_SHARED['first']; |
87 | $$ LANGUAGE 'plphp'; |
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88 | 1 | bford - | |
89 | SELECT set_var('hello plphp'); |
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90 | SELECT get_var(); -- will return 'hello plphp' |
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91 | }}} |
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92 | |||
93 | NOTE: The shared global variable is connection-specific. This is |
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94 | useful for passing information around a single script execution, |
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95 | 2 | Álvaro Herrera | but it is wiped when the connection is closed. |
96 | |||
97 | |||
98 | 3 | Álvaro Herrera | == PostgreSQL Array Support == |
99 | 1 | bford - | |
100 | There is support for multi-dimensional arrays. |
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101 | |||
102 | For example: |
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103 | |||
104 | {{{ |
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105 | 6 | Álvaro Herrera | CREATE FUNCTION php_array() RETURNS text[][] AS $$ |
106 | 1 | bford - | $return = array(array("Steven", "Klassen"), |
107 | array("Jonathan", "Daugherty")); |
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108 | |||
109 | return $return; |
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110 | 6 | Álvaro Herrera | $$ LANGUAGE 'plphp'; |
111 | 1 | bford - | }}} |
112 | |||
113 | |||
114 | {{{ |
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115 | sklassen=# select php_array(); |
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116 | php_array |
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117 | ----------------------------------------- |
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118 | {{Steven,Klassen},{Jonathan,Daugherty}} |
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119 | (1 row) |
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120 | }}} |
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121 | |||
122 | |||
123 | 3 | Álvaro Herrera | == Polymorphic Arguments and Return Types == |
124 | 1 | bford - | |
125 | Functions may be declared to accept and return the polymorphic types |
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126 | 'anyelement', 'anyarray', and 'anyrecord'. See the PostgreSQL |
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127 | documentation section 33.2.5 for a more detailed explanation of |
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128 | polymorphic functions. |
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129 | |||
130 | For example, |
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131 | |||
132 | {{{ |
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133 | CREATE FUNCTION array_three_values(anyelement, anyelement, anyelement) RETURNS anyarray AS ' |
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134 | $ret[0] = $args[0]; |
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135 | $ret[1] = $args[1]; |
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136 | $ret[2] = $args[2]; |
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137 | return $ret; |
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138 | ' LANGUAGE 'plphp'; |
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139 | |||
140 | SELECT array_three_values(3,2,1); |
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141 | array_three_values |
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142 | -------------------- |
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143 | {3,2,1} |
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144 | (1 row) |
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145 | |||
146 | CREATE OR REPLACE FUNCTION php_row(integer) RETURNS record AS ' |
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147 | $ret[f1]=$args[0]; |
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148 | $ret[f2]="hello"; |
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149 | $ret[f3]="world"; |
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150 | return $ret; |
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151 | ' LANGUAGE 'plphp'; |
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152 | |||
153 | select * FROM php_row(1) AS (f1 integer, f2 text, f3 text); |
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154 | }}} |
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155 | |||
156 | |||
157 | == Database Access (SPI) == |
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158 | |||
159 | 12 | Álvaro Herrera | Some functions are provided for database access. |
160 | 1 | bford - | |
161 | 12 | Álvaro Herrera | 1. spi_exec - Execute a query with optional limit. |
162 | 1 | bford - | {{{ |
163 | 12 | Álvaro Herrera | resource spi_exec(string query[, int limit]) |
164 | 1 | bford - | }}} |
165 | 1. spi_fetch_row - Return an associative array of the row's results. |
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166 | {{{ |
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167 | array spi_fetch_row(resource result) |
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168 | }}} |
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169 | 12 | Álvaro Herrera | 1. spi_status - Return the status of a previous query. If this is SPI_OK_SELECT you can obtain tuples from the result using spi_fetch_row. |
170 | {{{ |
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171 | string spi_status(resource result) |
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172 | }}} |
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173 | 1. spi_processed - Return the number of tuples in a result. |
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174 | {{{ |
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175 | int spi_processed(resource result) |
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176 | }}} |
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177 | 1. spi_rewind - Put the row cursor at the beginning of the result, so spi_fetch_row will continue fetching tuples from the beginning of the result. |
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178 | {{{ |
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179 | void spi_rewind(resource result) |
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180 | }}} |
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181 | 1 | bford - | |
182 | For example: |
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183 | |||
184 | This isn't a particularly useful function, but it will illustrate the |
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185 | above-described access functions. You provide an integer id and it |
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186 | returns the username text field. |
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187 | |||
188 | {{{ |
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189 | 12 | Álvaro Herrera | CREATE FUNCTION get_username(integer) RETURNS text AS $$ |
190 | 1 | bford - | # Assign the query to a variable. |
191 | $query = "SELECT username FROM users WHERE id = " .$args[0]; |
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192 | |||
193 | # Run the query and get the $result object. |
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194 | $result = spi_exec_query($query); |
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195 | |||
196 | # Fetch the row from the $result. |
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197 | $row = spi_fetch_row($result); |
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198 | |||
199 | 12 | Álvaro Herrera | return $row['username']; |
200 | $$ LANGUAGE 'plphp'; |
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201 | 1 | bford - | |
202 | sklassen=# select get_username(1); |
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203 | get_username |
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204 | -------------- |
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205 | sklassen |
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206 | (1 row) |
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207 | }}} |
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208 | |||
209 | 14 | Álvaro Herrera | Note that results from spi_exec_query are allocated in RAM as a whole, so if you need to process huge result sets, you need to use a cursor. This is not possible with the current interface however, so if you need to do this, bug the developers. |
210 | |||
211 | 1 | bford - | == Triggers == |
212 | 4 | Álvaro Herrera | |
213 | 1 | bford - | When a function is being used to return a trigger, the associative |
214 | array $_TD contains trigger-related values. |
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215 | |||
216 | 4 | Álvaro Herrera | $_TD["new"]:: |
217 | 1 | bford - | An associative array containing the values of the new table row for |
218 | INSERT/UPDATE actions, or empty for DELETE. The array is indexed |
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219 | by field name. Important note: Fields that are NULL will not |
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220 | appear in the array! |
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221 | 4 | Álvaro Herrera | $_TD["old"]:: |
222 | 1 | bford - | An associative array containing the values of the old table row for |
223 | 9 | Álvaro Herrera | UPDATE/DELETE actions, or empty for INSERT. The array is indexed |
224 | 1 | bford - | by field name. Important note: Fields that are NULL will not |
225 | appear in the array! |
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226 | 9 | Álvaro Herrera | $_TD["name"]:: |
227 | 1 | bford - | Contains the trigger name itself. |
228 | 4 | Álvaro Herrera | $_TD["event"]:: |
229 | 9 | Álvaro Herrera | Contains one of the values: "INSERT", "UPDATE", "DELETE". |
230 | 1 | bford - | $_TD["when"]:: |
231 | 4 | Álvaro Herrera | Contains one of the values: "BEFORE", "AFTER". |
232 | 1 | bford - | $_TD["level"]:: |
233 | Contains one of the values: "ROW", "STATEMENT". |
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234 | $_TD["relid"]:: |
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235 | Contains the relation ID of the table on which the trigger occured. |
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236 | 4 | Álvaro Herrera | $_TD["relname"]:: |
237 | 1 | bford - | Contains the relation name. |
238 | 15 | Álvaro Herrera | |
239 | 10 | Álvaro Herrera | $_TD["args"]:: |
240 | 1 | bford - | An array of arguments passed to the trigger, if any. They can be |
241 | 12 | Álvaro Herrera | accessed as $_TD["args"][idx]. For example, $_TD["args"]![0]. |
242 | 1 | bford - | $_TD["argc"]:: |
243 | 12 | Álvaro Herrera | The number of arguments passed to the trigger, 0 if none. |
244 | 4 | Álvaro Herrera | |
245 | 1 | bford - | === Example of an AFTER INSERT trigger === |
246 | 2 | Álvaro Herrera | |
247 | 1 | bford - | Suppose you have a users table with the typical columns and an |
248 | 3 | Álvaro Herrera | activity table that you're using to track page accesses. On row |
249 | 1 | bford - | |
250 | INSERT to the activity table, you want to update the last_seen field |
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251 | of the appropriate user's record. |
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252 | |||
253 | Consider the following table definitions: |
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254 | |||
255 | {{{ |
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256 | CREATE TABLE users ( |
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257 | id serial PRIMARY KEY NOT NULL, |
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258 | username text NOT NULL, |
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259 | email text, |
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260 | last_seen timestamp without time zone, |
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261 | active boolean DEFAULT true NOT NULL |
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262 | ); |
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263 | |||
264 | CREATE TABLE activity ( |
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265 | id serial PRIMARY KEY NOT NULL, |
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266 | users_id integer NOT NULL, |
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267 | file_accessed text NOT NULL, |
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268 | stamp timestamp without time zone DEFAULT now() NOT NULL, |
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269 | CONSTRAINT users_id_exists FOREIGN KEY (users_id) REFERENCES users(id) |
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270 | ); |
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271 | |||
272 | 13 | Álvaro Herrera | CREATE FUNCTION update_lastseen() RETURNS trigger AS $$ |
273 | $new =& $_TD['new']; |
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274 | 1 | bford - | |
275 | 13 | Álvaro Herrera | if (isset($new['users_id']) && isset($new['stamp'])) { |
276 | $query = "UPDATE users SET last_seen = '" .$new['stamp']. |
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277 | "' WHERE id = " .$new['users_id']; |
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278 | 1 | bford - | |
279 | 13 | Álvaro Herrera | $rv = spi_exec($query); |
280 | 1 | bford - | } |
281 | |||
282 | return; |
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283 | 13 | Álvaro Herrera | $$ LANGUAGE 'plphp'; |
284 | 1 | bford - | |
285 | CREATE TRIGGER after_update_lastseen_trigger |
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286 | AFTER INSERT ON activity FOR EACH ROW EXECUTE PROCEDURE update_lastseen(); |
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287 | |||
288 | }}} |
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289 | |||
290 | '''1. We'll insert a new user row.''' |
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291 | |||
292 | |||
293 | {{{ |
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294 | sklassen=# insert into users (username, email) values ('sklassen','sklassen@commandprompt.com'); |
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295 | INSERT 1 |
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296 | |||
297 | sklassen=# select * from users where username = 'sklassen'; |
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298 | |||
299 | id | username | email | last_seen | active |
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300 | ----+----------+----------------------------+-----------+-------- |
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301 | 1 | sklassen | sklassen@commandprompt.com | | t |
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302 | (1 row) |
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303 | }}} |
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304 | |||
305 | |||
306 | '''2. Insert a new row into the activity table.''' |
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307 | |||
308 | |||
309 | {{{ |
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310 | sklassen=# insert into activity (users_id, file_accessed) values (1,'index.html'); |
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311 | INSERT 1 |
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312 | }}} |
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313 | |||
314 | '''3. Check and make sure our trigger fired as expected.''' |
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315 | |||
316 | {{{ |
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317 | sklassen=# select * from users where username = 'sklassen'; |
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318 | id | username | email | last_seen | active |
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319 | ----+----------+----------------------------+----------------------------+-------- |
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320 | 1 | sklassen | sklassen@commandprompt.com | 2005-01-10 09:48:57.191595 | t |
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321 | (1 row) |
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322 | }}} |
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323 | |||
324 | === Example of a BEFORE INSERT OR UPDATE trigger === |
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325 | |||
326 | Let's say we have a user named admin that we want to prevent the |
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327 | 12 | Álvaro Herrera | application from modifying. We'll create a BEFORE DELETE trigger that |
328 | 1 | bford - | prevents them from deleting the row and a BEFORE UPDATE trigger that |
329 | prevents them modifying the username on which the previous trigger |
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330 | depends. |
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331 | |||
332 | {{{ |
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333 | 12 | Álvaro Herrera | CREATE TABLE users (username text, email text); |
334 | INSERT INTO users VALUES ('admin', 'admin@commandprompt.com'); |
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335 | INSERT INTO users VALUES ('darcy', 'darcy@example.com'); |
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336 | |||
337 | CREATE OR REPLACE FUNCTION immortal() RETURNS trigger AS $$ |
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338 | 1 | bford - | # The record may not be deleted if the username is "admin". |
339 | 12 | Álvaro Herrera | if ($_TD['old']['username'] == 'admin') { |
340 | pg_raise('notice', "You cannot delete the admin user"); |
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341 | return 'SKIP'; |
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342 | } |
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343 | return; |
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344 | $$ LANGUAGE 'plphp'; |
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345 | 1 | bford - | |
346 | CREATE TRIGGER before_delete_immortal_trigger BEFORE DELETE ON users |
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347 | FOR EACH ROW EXECUTE PROCEDURE immortal(); |
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348 | |||
349 | 12 | Álvaro Herrera | CREATE OR REPLACE FUNCTION protect_admin() RETURNS trigger AS $$ |
350 | 1 | bford - | # Do not let them modify the username of the admin account. |
351 | 12 | Álvaro Herrera | $oldUsername = $_TD['old']['username']; |
352 | $newUsername = $_TD['new']['username']; |
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353 | 1 | bford - | |
354 | 12 | Álvaro Herrera | if ($oldUsername == 'admin' && ($oldUsername != $newUsername)) { |
355 | pg_raise('notice', "You cannot change the admin username."); |
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356 | return 'SKIP'; |
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357 | 1 | bford - | } else { |
358 | 12 | Álvaro Herrera | return; |
359 | 1 | bford - | } |
360 | 12 | Álvaro Herrera | $$ LANGUAGE 'plphp'; |
361 | 1 | bford - | |
362 | CREATE TRIGGER before_update_protect_admin_trigger BEFORE UPDATE ON |
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363 | users FOR EACH ROW EXECUTE PROCEDURE protect_admin(); |
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364 | 12 | Álvaro Herrera | }}} |
365 | 1 | bford - | |
366 | 12 | Álvaro Herrera | Now the user admin cannot be deleted, nor its username can be changed: |
367 | |||
368 | {{{ |
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369 | pl_regression=# select * from users; |
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370 | username | email |
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371 | ----------+------------------------- |
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372 | admin | admin@commandprompt.com |
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373 | darcy | darcy@example.com |
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374 | 1 | bford - | (2 rows) |
375 | |||
376 | 12 | Álvaro Herrera | pl_regression=# update users set username = 'foobar'; |
377 | NOTICE: plphp: You cannot change the admin username. |
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378 | UPDATE 1 |
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379 | 1 | bford - | |
380 | 12 | Álvaro Herrera | pl_regression=# select * from users; |
381 | username | email |
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382 | ----------+------------------------- |
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383 | admin | admin@commandprompt.com |
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384 | foobar | darcy@example.com |
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385 | (2 rows) |
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386 | 1 | bford - | |
387 | 12 | Álvaro Herrera | pl_regression=# delete from users; |
388 | NOTICE: plphp: You cannot delete the admin user |
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389 | DELETE 1 |
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390 | |||
391 | pl_regression=# select * from users; |
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392 | username | email |
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393 | ----------+------------------------- |
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394 | admin | admin@commandprompt.com |
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395 | (1 row) |
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396 | 1 | bford - | }}} |
397 | |||
398 | |||
399 | == Trusted vs. Untrusted == |
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400 | |||
401 | Normally, PL/php is installed as a "trusted" procedural language named |
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402 | 'plphp'. In this configuration, PHP will run in "safe mode". Read |
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403 | more about the restrictions here: |
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404 | |||
405 | http://www.php.net/manual/en/features.safe-mode.functions.php |
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406 | |||
407 | In general, the operations that are restricted are those that interact |
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408 | with the environment. This includes file operations, require, and use |
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409 | (for external modules). |
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410 | |||
411 | Since there is no way to gain access to the internals of the database |
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412 | backend process or the operating system itself, any unprivileged |
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413 | database user may use functions written in this language. |
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414 | |||
415 | An example of a NON-working function due to security constraints: |
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416 | |||
417 | {{{ |
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418 | CREATE FUNCTION read_passwd_file() RETURNS text AS ' |
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419 | readfile("/etc/passwd"); |
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420 | return 0; |
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421 | ' LANGUAGE 'plphp'; |
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422 | }}} |
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423 | |||
424 | It will appear to execute, but depending on your log level, you'll may |
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425 | see something like the following: |
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426 | |||
427 | {{{ |
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428 | Warning: readfile(): SAFE MODE Restriction in effect. The script |
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429 | whose uid is 500 is not allowed to access /etc/passwd owned by uid 0 |
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430 | in Command line code on line 3 |
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431 | |||
432 | Warning: readfile(/etc/passwd): failed to open stream: Success in |
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433 | 4 | Álvaro Herrera | plphp function source on line 3 |
434 | }}} |
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435 | 1 | bford - | |
436 | Sometimes it is desirable to write PHP functions that are not |
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437 | restricted. In this case, you can create the language as 'plphpu' to |
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438 | enable the previously unavailable functions. |
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439 | |||
440 | {{{ |
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441 | 12 | Álvaro Herrera | CREATE LANGUAGE plphpu; |
442 | 1 | bford - | }}} |
443 | 4 | Álvaro Herrera | |
444 | 1 | bford - | |
445 | == Composite Type Arguments == |
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446 | |||
447 | Composite-type arguments are passed to the function as associative |
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448 | array. The keys of the array are the attribute names of |
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449 | the composite type. Here is an example: |
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450 | |||
451 | {{{ |
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452 | CREATE TABLE employee ( |
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453 | name text, |
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454 | basesalary integer, |
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455 | bonus integer |
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456 | ); |
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457 | |||
458 | CREATE FUNCTION empcomp(employee) RETURNS integer AS ' |
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459 | return $args[0][''basesalary''] + $args[0][''bonus'']; |
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460 | ' LANGUAGE 'plphp'; |
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461 | |||
462 | 12 | Álvaro Herrera | INSERT INTO employee values ('Josh', 1000, 10); |
463 | INSERT INTO employee values ('Darcy', 500, 20); |
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464 | |||
465 | 1 | bford - | SELECT name, empcomp(employee) FROM employee; |
466 | 12 | Álvaro Herrera | }}} |
467 | 1 | bford - | |
468 | 12 | Álvaro Herrera | This example results in the following output: |
469 | |||
470 | {{{ |
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471 | name | empcomp |
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472 | -------+--------- |
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473 | Josh | 1010 |
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474 | Darcy | 520 |
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475 | (2 rows) |
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476 | 1 | bford - | }}} |
477 | |||
478 | == Returning A Row (composite type) == |
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479 | |||
480 | To return a row or composite-type value from a PL/php-language |
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481 | function, you can use an indexed array: |
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482 | |||
483 | {{{ |
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484 | 12 | Álvaro Herrera | CREATE TYPE php_row AS (f1 integer, f2 text, f3 text); |
485 | 1 | bford - | |
486 | 12 | Álvaro Herrera | CREATE OR REPLACE FUNCTION php_row(integer) RETURNS php_row AS $$ |
487 | $ret['f1'] = $args[0]; |
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488 | $ret['f3'] = "world"; |
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489 | $ret['f2'] = "hello"; |
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490 | 1 | bford - | return $ret; |
491 | 12 | Álvaro Herrera | $$ LANGUAGE 'plphp'; |
492 | 1 | bford - | |
493 | 12 | Álvaro Herrera | SELECT * FROM php_row(1); |
494 | }}} |
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495 | 6 | Álvaro Herrera | |
496 | 1 | bford - | Will return: |
497 | 12 | Álvaro Herrera | {{{ |
498 | 6 | Álvaro Herrera | f1 | f2 | f3 |
499 | 2 | Álvaro Herrera | ----+-------+------- |
500 | 1 | bford - | 1 | hello | world |
501 | }}} |
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502 | |||
503 | |||
504 | == Returning multiple rows (SRF functions) == |
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505 | |||
506 | SRF stands for "set-returning functions". This means you can return |
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507 | 2 | Álvaro Herrera | multiple rows, like in the following example: |
508 | 1 | bford - | |
509 | {{{ |
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510 | 15 | Álvaro Herrera | CREATE TYPE php_row AS (f1 integer, f2 text, f3 text); |
511 | 1 | bford - | |
512 | 15 | Álvaro Herrera | CREATE OR REPLACE FUNCTION php_set(integer) RETURNS SETOF php_row AS $$ |
513 | 14 | Álvaro Herrera | $ret['f1'] = $args[0]; |
514 | $ret['f2'] = "hello"; |
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515 | $ret['f3'] = "world"; |
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516 | return_next($ret); |
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517 | 1 | bford - | |
518 | 14 | Álvaro Herrera | $ret['f1'] = 2 * $args[0]; |
519 | $ret['f2'] = "hello"; |
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520 | $ret['f3'] = "postgres"; |
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521 | return_next($ret); |
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522 | 1 | bford - | |
523 | 14 | Álvaro Herrera | $ret['f1'] = 3 * $args[0]; |
524 | $ret['f2'] = "hello"; |
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525 | $ret['f3'] = "plphp"; |
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526 | return_next($ret); |
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527 | $$ LANGUAGE 'plphp'; |
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528 | }}} |
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529 | 1 | bford - | |
530 | 14 | Álvaro Herrera | This will result in: |
531 | {{{ |
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532 | pl_regression=# SELECT * FROM php_set(1); |
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533 | 1 | bford - | f1 | f2 | f3 |
534 | ----+-------+---------- |
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535 | 1 | hello | world |
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536 | 3 | Álvaro Herrera | 2 | hello | postgres |
537 | 1 | bford - | 3 | hello | plphp |
538 | 14 | Álvaro Herrera | (3 rows) |
539 | 1 | bford - | }}} |
540 | 3 | Álvaro Herrera | |
541 | 14 | Álvaro Herrera | The important thing to notice here is the `return_next()` function. This function must be called with a single parameter, which must be an array with one element per attribute of the return type. Note that currently the names of the array elements are ignored; the elements are assigned to attributes in order. If you must return a null value, asign a null value to an array element. This may be fixed in a future release. |
542 | |||
543 | Finishing a SRF is done by either calling `return` or by falling off the end of the function. At that point the entire results are delivered back to the outer query, be it directly to the user or to be joined to other tables/SRFs/etc. |
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544 | |||
545 | The return tuples are written to a Postgres "tuplestore", which is disk-backed, and thus do not need to fit entirely in RAM. |
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546 | |||
547 | 12 | Álvaro Herrera | == Limitations == |
548 | 1 | bford - | |
549 | PL/php functions cannot call each other directly because their names |
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550 | are mangled. |
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551 | 14 | Álvaro Herrera | |
552 | SPI calls have the whole results allocated in memory, so processing huge results may be problematic. Also it's not possible to use cursors with SPI. |