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1 ====================================
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2 MySQLdb Frequently Asked Questions
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3 ====================================
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4
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5 .. contents::
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6 ..
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7
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8
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9 Build Errors
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10 ------------
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11
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12 ld: fatal: library -lmysqlclient_r: not found
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13
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14 mysqlclient_r is the thread-safe library. It's not available on
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15 all platforms, or all installations, apparently. You'll need to
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16 reconfigure site.cfg (in MySQLdb-1.2.1 and newer) to have
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17 threadsafe = False.
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18
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19 mysql.h: No such file or directory
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20
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21 This almost always mean you don't have development packages
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22 installed. On some systems, C headers for various things (like MySQL)
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23 are distributed as a seperate package. You'll need to figure out
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24 what that is and install it, but often the name ends with -devel.
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25
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26 Another possibility: Some older versions of mysql_config behave oddly
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27 and may throw quotes around some of the path names, which confused
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28 MySQLdb-1.2.0. 1.2.1 works around these problems. If you see things
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29 like -I'/usr/local/include/mysql' in your compile command, that's
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30 probably the issue, but it shouldn't happen any more.
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31
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32
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33 ImportError
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34 -----------
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35
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36 ImportError: No module named _mysql
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37
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38 If you see this, it's likely you did some wrong when installing
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39 MySQLdb; re-read (or read) README. _mysql is the low-level C module
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40 that interfaces with the MySQL client library.
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41
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42 Various versions of MySQLdb in the past have had build issues on
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43 "weird" platforms; "weird" in this case means "not Linux", though
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44 generally there aren't problems on Unix/POSIX platforms, including
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45 BSDs and Mac OS X. Windows has been more problematic, in part because
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46 there is no `mysql_config` available in the Windows installation of
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47 MySQL. 1.2.1 solves most, if not all, of these problems, but you will
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48 still have to edit a configuration file so that the setup knows where
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49 to find MySQL and what libraries to include.
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50
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51
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52 ImportError: libmysqlclient_r.so.14: cannot open shared object file: No such file or directory
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53
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54 The number after .so may vary, but this means you have a version of
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55 MySQLdb compiled against one version of MySQL, and are now trying to
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56 run it against a different version. The shared library version tends
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57 to change between major releases.
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58
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59 Solution: Rebuilt MySQLdb, or get the matching version of MySQL.
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60
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61 Another thing that can cause this: The MySQL libraries may not be on
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62 your system path.
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63
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64 Solutions:
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65
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66 * set the LD_LIBRARY_PATH environment variable so that it includes
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67 the path to the MySQL libraries.
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68
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69 * set static=True in site.cfg for static linking
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70
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71 * reconfigure your system so that the MySQL libraries are on the
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72 default loader path. In Linux, you edit /etc/ld.so.conf and run
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73 ldconfig. For Solaris, see `Linker and Libraries Guide
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74 <http://docs.sun.com/app/docs/doc/817-3677/6mj8mbtbe?a=view>`_.
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75
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76
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77 ImportError: ld.so.1: python: fatal: libmtmalloc.so.1: DF_1_NOOPEN tagged object may not be dlopen()'ed
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78
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79 This is a weird one from Solaris. What does it mean? I have no idea.
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80 However, things like this can happen if there is some sort of a compiler
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81 or environment mismatch between Python and MySQL. For example, on some
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82 commercial systems, you might have some code compiled with their own
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83 compiler, and other things compiled with GCC. They don't always mesh
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84 together. One way to encounter this is by getting binary packages from
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85 different vendors.
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86
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87 Solution: Rebuild Python or MySQL (or maybe both) from source.
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88
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89 ImportError: dlopen(./_mysql.so, 2): Symbol not found: _sprintf$LDBLStub
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90 Referenced from: ./_mysql.so
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91 Expected in: dynamic lookup
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92
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93 This is one from Mac OS X. It seems to have been a compiler mismatch,
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94 but this time between two different versions of GCC. It seems nearly
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95 every major release of GCC changes the ABI in some why, so linking
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96 code compiled with GCC-3.3 and GCC-4.0, for example, can be
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97 problematic.
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98
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99
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100 My data disappeared! (or won't go away!)
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101 ----------------------------------------
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102
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103 Starting with 1.2.0, MySQLdb disables autocommit by default, as
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104 required by the DB-API standard (`PEP-249`_). If you are using InnoDB
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105 tables or some other type of transactional table type, you'll need
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106 to do connection.commit() before closing the connection, or else
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107 none of your changes will be written to the database.
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108
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109 Conversely, you can also use connection.rollback() to throw away
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110 any changes you've made since the last commit.
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111
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112 Important note: Some SQL statements -- specifically DDL statements
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113 like CREATE TABLE -- are non-transactional, so they can't be
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114 rolled back, and they cause pending transactions to commit.
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115
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116
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117 Other Errors
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118 ------------
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119
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120 OperationalError: (1251, 'Client does not support authentication protocol requested by server; consider upgrading MySQL client')
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121
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122 This means your server and client libraries are not the same version.
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123 More specifically, it probably means you have a 4.1 or newer server
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124 and 4.0 or older client. You can either upgrade the client side, or
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125 try some of the workarounds in `Password Hashing as of MySQL 4.1
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126 <http://dev.mysql.com/doc/refman/5.0/en/password-hashing.html>`_.
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127
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128
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129 Other Resources
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130 ---------------
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131
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132 * Help forum. Please search before posting.
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133
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134 * `Google <http://www.google.com/>`_
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135
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136 * READ README!
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137
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138 * Read the User's Guide
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139
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140 * Read `PEP-249`_
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141
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142 .. _`PEP-249`: http://www.python.org/peps/pep-0249.html
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143
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