您可以根据用于 spool 的视图生成外部表。
同样p_view_name
,您只需执行一次,即使p_timestamp
更改了新的提取,您也可以更改现有的永恒表:
alter table ext_table location ('new_filename');
如果 p_view_name
发生更改,则必须重新运行表生成脚本。
我提供的解决方案只有在数据文件中的每一列在所有行中都具有固定长度时才有效。
首先,您必须生成一个“列列表视图” - 包含所有声明的列名和源视图长度的扁平结构。
/* Execute:
sqlplus scott/tiger@orcl1 @gen_column_list_view_ddl.sql
*/
SET SQLBLANKLINES ON
SET PAGESIZE 0 FEEDBACK OFF
SET TRIMSPOOL ON LINE 32000
SET WRAP ON
SET NEWPAGE NONE
SET PAGESIZE 0
SET SPACE 0 LONG 1000
SET ECHO OFF
SET FEEDBACK OFF
SET VERIFY OFF
SET HEADING OFF
set termout off
spool GENERATE_EXTERNAL_TABLE/GENERATED/v_column_list.sql
PROMPT set sqlblanklines on
select '
create or replace view v_column_list
as select ' from dual
union all
select ''''||column_name||''' '||column_name||', length('||column_name||') "'||column_name||'_len"'||(case cid when max_cid then '' else ',' end) len
from
(select column_id cid, max(column_id) over() max_cid,column_name
from all_tab_columns
where table_name=:source_view order by column_id)
union all
select '
from '||:source_view||'
where rownum <2' from dual;
PROMPT /
--PROMPT exit;;
spool off
因为您在没有分隔符的情况下进行提取,这意味着它的长度固定,并且对于给定列的所有行,实际数据大小相同。
第二步是“列长视图”生成。因为给定列的声明数据长度可能与实际数据长度不同,我们必须创建另一个视图来修复它。
/* Execute:
sqlplus scott/tiger@orcl1 @gen_col_len_view_ddl.sql
*/
SET SQLBLANKLINES ON HEAD OFF
SET PAGESIZE 0 FEEDBACK OFF
SET TRIMSPOOL ON LINE 32000
SET WRAP ON
SET NEWPAGE NONE
SET PAGESIZE 0
SET SPACE 0 LONG 1000
SET ECHO OFF
SET FEEDBACK OFF
SET VERIFY OFF
SET HEADING OFF
set termout off
spool GENERATE_EXTERNAL_TABLE/GENERATED/v_col_len.sql
PROMPT set sqlblanklines on
select '
create or replace view v_col_len as
select rn1,col_name,col_len
from( select rownum rn1,value col_name
from (select * from v_column_list
unpivot ( value
for value_type in (' str
from dual
union all
select '"'||column_name||'"'||(case cid when max_cid then '' else ',' end) len
from
(select column_id cid, max(column_id) over() max_cid,column_name
from all_tab_columns
where table_name=:source_view
order by column_id)
union all
select ')
))),
(select rownum rn2, value col_len
from ( select * from v_column_list
unpivot ( value for value_type in ('
from dual
union all
select '"'||column_name||'_len"'||(case cid when max_cid then '' else ',' end) len
from
(select column_id cid, max(column_id) over() max_cid,column_name
from all_tab_columns
where table_name=:source_view
order by column_id)
union all
select ')
)))
where rn1=rn2 ' from dual;
PROMPT /
--PROMPT exit;;
spool off
现在我们知道一列在哪里结束,另一列从哪里开始,我们可以生成外部表 DDL
/* Execute:
sqlplus scott/tiger@orcl1 @gen_external_table_ddl.sql
*/
COLUMN str format a900
set termout on
PROMPT Generating ext table DDL
set termout off
SET SQLBLANKLINES ON
SET PAGESIZE 0
SET TRIMSPOOL ON LINE 32000
SET WRAP ON
SET NEWPAGE NONE
SET PAGESIZE 0
SET SPACE 0
SET LINESIZE 16000
SET ECHO OFF
SET FEEDBACK OFF
SET VERIFY OFF
SET HEADING OFF
set timing off
set time off
set headsep off
set termout off
spool GENERATE_EXTERNAL_TABLE/GENERATED/fixed_width_external_table.sql
PROMPT set sqlblanklines on
PROMPT set termout on
PROMPT PROMPT Creating external table
WITH c as (select * from V_COL_LEN)
select 'DROP TABLE '||:ext_table_name||';' str from dual
union all
select '
set termout off
CREATE TABLE '||:ext_table_name||'
( '
str
from dual union all
select col_name||' CHAR('||col_len||')'||(case rn1 when max_rn then '' else ',' end) str from
(
select col_name,col_len, rn1, max(rn1) over() max_rn
from c)
union all
select ' )
ORGANIZATION external
(
TYPE oracle_loader
DEFAULT DIRECTORY TEST_DIR
ACCESS PARAMETERS
(
RECORDS DELIMITED BY NEWLINE CHARACTERSET WE8ISO8859P1
READSIZE 1048576
FIELDS LDRTRIM
MISSING FIELD VALUES ARE NULL
REJECT ROWS WITH ALL NULL FIELDS
('
from dual
union all
select col_name||' ('||(CUMTOT-col_len+1)||':'||CUMTOT||') CHAR('||col_len||')'||(case rn1 when max_rn then '' else ',' end) str from (
select col_name,col_len,
SUM(col_len) OVER (ORDER BY rn1) CUMTOT, rn1, max(rn1) over() max_rn
from c)
union all
select ')
)
location
(
'''||:dump_file_name||'''
)
)
'
from dual
/
PROMPT /
--PROMPT exit;;
spool off
要结束它,您可以创建执行所有 3 个步骤的独立脚本。
var dump_file_name varchar2(128);
BEGIN
select 'c_'||export_date||'.dmp' into :dump_file_name
from (select
to_char(sd,'MM')||to_char(sd,'YY') export_date
from (SELECT systimestamp sd FROM DUAL));
END;
/
print :dump_file_name
var ext_table_name varchar2(32);
BEGIN
select 'fixed_width_external_table' into :ext_table_name from dual;
END;
/
print :ext_table_name
var source_view varchar2(32);
BEGIN
select 'V_TEST' into :source_view from dual;
END;
/
print :source_view
PROMPT Generating column list view (V_COLUMN_LIST) based on source view
@GENERATE_EXTERNAL_TABLE/gen_column_list_view_ddl.sql
@GENERATE_EXTERNAL_TABLE/GENERATED/v_column_list.sql
PROMPT Generating column lengths view (V_COL_LEN) based on source view
@GENERATE_EXTERNAL_TABLE/gen_col_len_view_ddl.sql
@GENERATE_EXTERNAL_TABLE/GENERATED/v_col_len.sql
PROMPT Generating external table DDL based on V_COL_LEN
@GENERATE_EXTERNAL_TABLE/gen_external_table_ddl.sql
@GENERATE_EXTERNAL_TABLE/GENERATED/fixed_width_external_table.sql
SET PAGESIZE 99
SET ECHO on
SET FEEDBACK on
SET VERIFY OFF
SET HEADING on
set timing on
set time on
set headsep on
set termout on
var exported_cnt varchar2(32);
BEGIN
EXECUTE IMMEDIATE 'select /*+PARALLEL (t,auto)*/ count(*) rows_exported from '||:ext_table_name||' t' INTO :exported_cnt;
END;
/
print :exported_cnt
此脚本将从 Oracle 中的现有视图或堆表名称创建外部表 DDL。
我最初为 Oracle 中的常规到外部表转换编写了 if。