python – postgres plpy.execute与hstore字符串文字失败

2023年2月17日 376次阅读

我正在使用
postgresql 9.2编写一个pl
python函数.假设代码已经执行了返回hstore字符串的查询.我希望然后发出一个查询：

SELECT hstore_to_matrix('hstorestring')

假设它是一个包含hstore字符串的字符串：A => B.

create or replace function testfreq() 
returns text
as $$
hstorestring = '"GT"=>"thing","HS"=>"[-0.1,-0.2]"'
rv2 = plpy.execute("SELECT hstore_to_matrix(%s)" % (plpy.quote_literal(hstorestring)))
plpy.log("Hstore:",rv2[0])
return("done")
$$LANGUAGE plpythonu;

运行为

select testfreq();

返回

testdb=# select testfreq();
ERROR:  plpy.Error: unrecognized error in PLy_spi_execute_fetch_result
CONTEXT:  Traceback (most recent call last):
PL/Python function "testfreq", line 3, in <module>
rv2 = plpy.execute("SELECT hstore_to_matrix(%s)" % (plpy.quote_literal(hstorestring)))
PL/Python function "testfreq":

如果在上面的代码中用hstore_to_array替换,则输出为：

testdb=# select testfreq();
LOG:  ('Hstore:', {'hstore_to_array': ['GT', 'thing', 'HS', '[-0.1,-0.2]']})
CONTEXT:  PL/Python function "testfreq"
testfreq 
----------
done
(1 row)

我也尝试使用hstore运算符而不是函数,我已经在pgsql终端中尝试了这些函数,以确保它们在没有嵌入python时工作.任何指针都将非常感激.

最佳答案 看起来PL / Python无法正确处理多维数组：

create or replace function testarray()
returns text
as $$
rv2 = plpy.execute("SELECT ARRAY[ ARRAY['1','2','3'], ARRAY['a','b','c'] ];" )
$$LANGUAGE plpythonu;

结果：

craig=# select testarray();
ERROR:  plpy.Error: unrecognized error in PLy_spi_execute_fetch_result
CONTEXT:  Traceback (most recent call last):
  PL/Python function "testarray", line 2, in <module>
    rv2 = plpy.execute("SELECT ARRAY[ ARRAY['1','2','3'], ARRAY['a','b','c'] ];" )
PL/Python function "testarray"

(经过Pg 9.2.4,Python 2.7.3测试).

hstore文本有效：

craig=# SELECT '"GT"=>"thing","HS"=>"[-0.1,-0.2]"'::hstore;
               hstore               
------------------------------------
 "GT"=>"thing", "HS"=>"[-0.1,-0.2]"
(1 row)

并且查询在PL / Python之外工作：

craig=# select hstore_to_matrix('"GT"=>"thing","HS"=>"[-0.1,-0.2]"');
        hstore_to_matrix         
---------------------------------
 {{GT,thing},{HS,"[-0.1,-0.2]"}}
(1 row)

进一步表明这是一个PL / Python问题.

您可以通过转换为文本然后在返回结果后转换回text []来解决此问题,尽管它效率低下：

create or replace function testfreq() 
returns text
as $$
hstorestring = '"GT"=>"thing","HS"=>"[-0.1,-0.2]"'
rv2 = plpy.execute("SELECT hstore_to_matrix(%s)::text" % (plpy.quote_literal(hstorestring)))
plpy.log("Hstore:",rv2[0])                                                                                                                                                     
return("done")                                                                                                                                                                 
$$LANGUAGE plpythonu;

结果：

craig=# SELECT testfreq();
 testfreq 
----------
 done
(1 row)
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