_php tutorials for reading files and reading error problems using PostgreSQL Bytea word Gencun

The Bytea field type in PostgreSQL can store data in binary form, and the benefit is that files stored in a Web site directory can be stored in a database, and the downside is that if the file is too large, it can result in a large increase in the amount of data in the database. Backup and recovery can waste a lot of time, and data can be error-prone. Personally, in the case of small file size, the use of this storage method is still very convenient.

To the bottom, the following describes the use of Bytea Word Gencun read the file implementation method. The first is the file stored in the Bytea field method, the main use of PHP is the Pg_escape_bytea method, the code is as follows:

!--?   = Pg_connect ("host= ' localhost ' dbname= ' dbname ' user= ' user ' password= ' password ' port= ' Port '" span) or Span> (' Could not connect: '.   =  ("Utf-8", "GBK", );  =  (
             
               = Pg_escape_bytea ();   = "} ') "
                     
                      , 
                         
                          
                            
                    

The Pg_unescape_bytea method in PHP is used to restore files from the Bytea field, and the implementation code is as follows:

 = Pg_connect ("host= ' localhost ' dbname= ' dbname ' user= ' user ' password= ' password ' port= ' Port '"
   
     (' Could not connect: '.   = "". ;   = pg_query (, 
              
                ( = Pg_fetch_array ( , , = [' contents ' 
                       
                        = Pg_unescape_bytea ();   (,  ); 
                                
                                 ?> 
                                      
                      
               
   

After exporting the file, if the binary data transcoding error occurs when the file is not open, such as the wrong PDF file opens with an error such as:

This error is particularly likely to occur when the database is migrated (I migrated from PostgreSQL 8.4 to 9.1), and the workaround is to modify the PostgreSQL configuration file
postgresql.conf, set the output type of the bytea_output to escape type (escape) output, that is, bytea_output = ' escape ' (if the previous #, remove the open configuration), Then reload the configuration of PostgreSQL to make the changes take effect so that the binary data can be decoded and output to the file normally.

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