Oracle Clob 类型检索比较

今天做了几个Clob类型数据的检索比较，结果如下：

1. Like 方式检索

    set timing on
    set lin 150 pages 999
    set autotrace traceonly
    select * from lob_tbl where upper(c) LIKE '%2022-04-01 02:05:31.709329%';
    
    経過: 00:00:02.24
    
    実行計画
    ----------------------------------------------------------
    Plan hash value: 1723626472
    
    -----------------------------------------------------------------------------
    | Id  | Operation         | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
    -----------------------------------------------------------------------------
    |   0 | SELECT STATEMENT  |         |     1 |  4017 |     3   (0)| 00:00:01 |
    |*  1 |  TABLE ACCESS FULL| LOB_TBL |     1 |  4017 |     3   (0)| 00:00:01 |
    -----------------------------------------------------------------------------
    
    Predicate Information (identified by operation id):
    ---------------------------------------------------
    
       1 - filter(UPPER("C") LIKE '%2022-04-01 02:05:31.709329%')
    
    Note
    -----
       - dynamic sampling used for this statement (level=2)
    
    
    統計
    ----------------------------------------------------------
             10  recursive calls
         335256  db block gets
         128501  consistent gets
          28998  physical reads
            124  redo size
           2368  bytes sent via SQL*Net to client
           1819  bytes received via SQL*Net from client
              7  SQL*Net roundtrips to/from client
              0  sorts (memory)
              0  sorts (disk)
              1  rows processed
          

2. dbms_lob.instr 方式检索

    alter system flush buffer_cache;
    select * from lob_tbl where dbms_lob.instr(c,'2022-04-01 02:05:31.70932')>0;
    
    経過: 00:00:00.18
    
    実行計画
    ----------------------------------------------------------
    Plan hash value: 1723626472
    
    -----------------------------------------------------------------------------
    | Id  | Operation         | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
    -----------------------------------------------------------------------------
    |   0 | SELECT STATEMENT  |         |     1 |  4017 |     3   (0)| 00:00:01 |
    |*  1 |  TABLE ACCESS FULL| LOB_TBL |     1 |  4017 |     3   (0)| 00:00:01 |
    -----------------------------------------------------------------------------
    
    Predicate Information (identified by operation id):
    ---------------------------------------------------
    
       1 - filter("DBMS_LOB"."INSTR"("C",'2022-04-01 02:05:31.70932')>0)
    
    Note
    -----
       - dynamic sampling used for this statement (level=2)
    

    
    統計
    ----------------------------------------------------------
            633  recursive calls
              0  db block gets
          47809  consistent gets
          14554  physical reads
              0  redo size
           2368  bytes sent via SQL*Net to client
           1819  bytes received via SQL*Net from client
              7  SQL*Net roundtrips to/from client
              0  sorts (memory)
              0  sorts (disk)
              1  rows processed

3. Text 方式检索

    CREATE INDEX Content_Tbl_Index ON lob_tbl (c) INDEXTYPE IS CTXSYS.CONTEXT;
    
    alter system flush buffer_cache;
    select * from lob_tbl where contains(c,'%2022-04-01 02:05:31.70932%')>0;
    
    経過: 00:00:00.11
    
    実行計画
    ----------------------------------------------------------
    Plan hash value: 1854112279
    
    -------------------------------------------------------------------------------------------------
    | Id  | Operation                   | Name              | Rows  | Bytes | Cost (%CPU)| Time     |
    -------------------------------------------------------------------------------------------------
    |   0 | SELECT STATEMENT            |                   |     1 |  4029 |     4   (0)| 00:00:01 |
    |   1 |  TABLE ACCESS BY INDEX ROWID| LOB_TBL           |     1 |  4029 |     4   (0)| 00:00:01 |
    |*  2 |   DOMAIN INDEX              | CONTENT_TBL_INDEX |       |       |     4   (0)| 00:00:01 |
    -------------------------------------------------------------------------------------------------
    
    Predicate Information (identified by operation id):
    ---------------------------------------------------
    
       2 - access("CTXSYS"."CONTAINS"("C",'%2022-04-01 02:05:31.70932%')>0)
    
    Note
    -----
       - dynamic sampling used for this statement (level=2)
    

    
    統計
    ----------------------------------------------------------
           2426  recursive calls
              0  db block gets
           5753  consistent gets
           2632  physical reads
              0  redo size
            615  bytes sent via SQL*Net to client
            524  bytes received via SQL*Net from client
              2  SQL*Net roundtrips to/from client
            221  sorts (memory)
              0  sorts (disk)
              0  rows processed