PSQL 函数不能转义引号

Posted 2023-03-28

【中文标题】PSQL 函数不能转义引号

【英文标题】：PSQL function cannot escaping quotes

【发布时间】：2018-05-08 06:04:51

【问题描述】：

我有如下查询。分析和比较不同服务器上同一张表的行数。它按预期工作，但如果有任何大小写混合的表名，例如：'stg.my_table_OTHER'，则会遇到问题。

如果我添加像 stg."my_table_OTHER" 这样的引号，它会起作用。但它似乎不适用于功能。已经尝试使用 '\"stg.my_table_OTHER\"' 逃脱，但仍然没有运气。

请在我的查询下方找到。

问候， 里安

CREATE OR REPLACE FUNCTION dwh.sync_update_analyze(schemaname varchar, tablename varchar)
        RETURNS integer AS $body$
        DECLARE

            passedSrc boolean;
            passedTgt boolean;
            rowcount bigint;                                                                                                  
            tgtcount bigint;
            query text; 
        BEGIN
            SELECT EXISTS (                                                                                                   
                    SELECT 1                                                                                                       
                    FROM   pg_catalog.pg_class c                                                                                   
                    JOIN   pg_catalog.pg_namespace n ON n.oid = c.relnamespace                                                     
                    WHERE  n.nspname = $1                                                                                          
                    AND    c.relname = $2                                                                                          
                    AND    c.relkind = 'r'    -- only tables                                                                       
            ) into passedSrc;

            passedTgt = ops.runcmd('psql -h 666.66.6.666 -Atc "SELECT EXISTS ( SELECT 1 FROM pg_catalog.pg_class c JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace WHERE n.nspname = ''' || schemaname || ''' AND c.relname = ''' || tablename || ''' AND c.relkind = ''r'');"');



            IF passedSrc = 't' and passedTgt = 't' THEN

            query = ops.runcmd('psql -h 666.66.6.666 -Atc "ANALYZE ' || schemaname || '.' || tablename || ';"'); 

                tgtcount = ops.runcmd('psql -h 666.66.6.666 -Atc "select count(*) from ' || schemaname || '.' || tablename || ';"'); 
                EXECUTE '(select count(1) from ' || quote_ident($1) || '.' || quote_ident($2) || ')' INTO rowcount;               
                         query := 'UPDATE dwh.table_list_2018 SET                                                                  
                         move_data_to_dca = ''D'',                                                                                 
                         row_count = '|| rowcount || ',
                         target_cnt = '|| tgtcount ||'
                         WHERE schema = ''' || $1 || ''' and table_name = ''' || $2 || '''';          
                         EXECUTE query;

            ELSE                                                                                                           
                         query := 'UPDATE dwh.table_list_2018 SET                                                                  
                         move_data_to_dca = ''D'',                                                                                 
                         purge_table = ''Y'',
                         backup_location = ''table maybe purge on source or relation doesnt exists''                                                                                       
                         WHERE schema = ''' || $1 || ''' and table_name = ''' || $2 || '''';          
                         EXECUTE query;                                                                                            

           END IF; 

                 return 0;

                    EXCEPTION WHEN OTHERS THEN
                 query := 'UPDATE dwh.table_list_2018 SET                                                                  
             move_data_to_dca = ''D'',                                                                                 
             purge_table = ''Y'',
             backup_location = ''table maybe purge on source or relation doesnt exists''                                                                                
             WHERE schema = ''' || $1 || ''' and table_name = ''' || $2 || '''';          
             EXECUTE query; 
             RETURN 1;


        END
        $body$ LANGUAGE plpgsql;

在这部分抛出错误

 tgtcount = ops.runcmd('psql -h 666.66.6.666 -Atc "select count(*) from ' || schemaname || '.' || tablename || ';"'); 

当我编辑到

 tgtcount = ops.runcmd('psql -h 666.66.6.666 -Atc "select count(*) from ' || schemaname || '.\"' || tablename || '\";"'); 

它抛出

 HINT:  Use the escape string syntax for escapes, e.g., E'\r\n'
 INT:  Use the escape string syntax for escapes, e.g., E'\r\n'.
 QUERY:  SELECT  ops.runcmd('psql -h 666.66.6.666 -Atc "select count(*) from ' ||  $1  || '.\"' ||  $2  || '\";"')
 CONTEXT:  SQL statement in PL/PgSQL function "sync_update_analyze1" near line 26
 WARNING:  nonstandard use of escape in a string literal

仅供参考。我正在使用

 "PostgreSQL 8.2.15 (Greenplum Database 4.3.18.0 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Nov 22 2017 18:54:31"

【参考方案1】：

我对greenplum一无所知，但如果它的行为类似于PostgreSQL，我会尝试这样：

tgtcount := ops.runcmd(
               'psql -h 666.66.6.666 -Atc ''select count(*) from '
               || quote_ident(schemaname) || '.'
               || quote_ident(tablename) || ';'''
            );

这样，您在 SQL 语句中使用单引号，这样就不会与 quote_ident 可能添加的双引号发生冲突。

【讨论】：

嗨，阿尔贝。感谢您的回复。我试过了，是的，它确实放了双引号，但它降低了大小写。并且仍然抛出错误预期的表不存在。

嗯，它在 PostgreSQL 中工作。考虑一下DO 声明：DO $$DECLARE s text := 'Schema'; t text := 'Table'; BEGIN RAISE NOTICE '%', 'psql -h 666.66.6.666 -Atc ''select count(*) from ' || quote_ident(s) || '.' || quote_ident(t) || ';'''; END;$$; 结果是：NOTICE: psql -h 666.66.6.666 -Atc 'select count(*) from "Schema"."Table";' 不知道你那边出了什么问题，但是我不知道ops.runcms 到底做了什么。

赋值给变量和 quote_ident 就可以了。现在可以了。谢谢大哥！

@ryanfauzi：如果你有答案，请考虑accepting it。