Kdb 从q中的表中软删除列

我试图在不丢失数据的情况下从表中删除一列，以便可以再次恢复数据，但当通过q进程加载表时，删除的列将不会显示。显然，我下面的代码将无法工作。q有什么特别的东西可以做到这一点吗？dir是表所在的位置，c是要删除的列

{[dir;t;c] delete c from (` sv (dir,t),`)}

kdb+有一种简单的方法可以“删除”列，而无需实际删除列数据。如果查看存储表的目录，应该能够识别

.d

文件。这是kdb+存储表列的正确顺序的地方。要删除列，只需从此

.d

文件中删除列名。例如：

q)get `:test/.d
`sym`time`src`bid`ask`bsize`asize
q)
q)`:test/.d set `sym`time`src`bid`ask`bsize
`:test/.d
q)
q)test
sym  time                          src bid   ask   bsize asize
--------------------------------------------------------------
AAPL 2014.04.21D08:00:00.456000000 L   25.32 25.36 8000  8500
AAPL 2014.04.21D08:00:01.387000000 O   25.32 25.35 9500  2500
AAPL 2014.04.21D08:00:10.348000000 N   25.35 25.35 8000  5000
AAPL 2014.04.21D08:00:10.532000000 L   25.33 25.37 5000  7000
AAPL 2014.04.21D08:00:15.163000000 L   25.34 25.36 10000 8000
AAPL 2014.04.21D08:00:15.847000000 N   25.32 25.36 1500  500
AAPL 2014.04.21D08:00:16.335000000 N   25.33 25.34 8500  5500
AAPL 2014.04.21D08:00:17.017000000 N   25.33 25.34 9000  2500
AAPL 2014.04.21D08:00:17.634000000 N   25.3  25.36 9500  1000
AAPL 2014.04.21D08:00:19.427000000 L   25.33 25.36 9500  5000
AAPL 2014.04.21D08:00:24.629000000 N   25.33 25.37 6000  2000
AAPL 2014.04.21D08:00:25.207000000 L   25.33 25.36 5000  2500
AAPL 2014.04.21D08:00:29.962000000 L   25.32 25.38 3500  5000
AAPL 2014.04.21D08:00:31.998000000 O   25.34 25.36 5500  4000
AAPL 2014.04.21D08:00:33.795000000 N   25.34 25.36 5000  3500
AAPL 2014.04.21D08:00:34.651000000 L   25.35 25.37 7500  6500
AAPL 2014.04.21D08:00:38.843000000 O   25.33 25.36 4000  6500
AAPL 2014.04.21D08:00:40.062000000 L   25.33 25.38 2000  9500
AAPL 2014.04.21D08:00:43.508000000 N   25.35 25.36 6500  10000
AAPL 2014.04.21D08:00:46.823000000 N   25.35 25.38 6000  7500
..
q)\l .
q)test
sym  time                          src bid   ask   bsize
--------------------------------------------------------
AAPL 2014.04.21D08:00:00.456000000 L   25.32 25.36 8000
AAPL 2014.04.21D08:00:01.387000000 O   25.32 25.35 9500
AAPL 2014.04.21D08:00:10.348000000 N   25.35 25.35 8000
AAPL 2014.04.21D08:00:10.532000000 L   25.33 25.37 5000
AAPL 2014.04.21D08:00:15.163000000 L   25.34 25.36 10000
AAPL 2014.04.21D08:00:15.847000000 N   25.32 25.36 1500
AAPL 2014.04.21D08:00:16.335000000 N   25.33 25.34 8500
AAPL 2014.04.21D08:00:17.017000000 N   25.33 25.34 9000

一旦删除，kdb+将不会将该列与表关联，并且在内存中调用时也不会显示该列

希望这能有所帮助。

kdb+有一种简单的方法可以“删除”列，而无需实际删除列数据。如果查看存储表的目录，应该能够识别

.d

文件。这是kdb+存储表列的正确顺序的地方。要删除列，只需从此

.d

文件中删除列名。例如：

q)get `:test/.d
`sym`time`src`bid`ask`bsize`asize
q)
q)`:test/.d set `sym`time`src`bid`ask`bsize
`:test/.d
q)
q)test
sym  time                          src bid   ask   bsize asize
--------------------------------------------------------------
AAPL 2014.04.21D08:00:00.456000000 L   25.32 25.36 8000  8500
AAPL 2014.04.21D08:00:01.387000000 O   25.32 25.35 9500  2500
AAPL 2014.04.21D08:00:10.348000000 N   25.35 25.35 8000  5000
AAPL 2014.04.21D08:00:10.532000000 L   25.33 25.37 5000  7000
AAPL 2014.04.21D08:00:15.163000000 L   25.34 25.36 10000 8000
AAPL 2014.04.21D08:00:15.847000000 N   25.32 25.36 1500  500
AAPL 2014.04.21D08:00:16.335000000 N   25.33 25.34 8500  5500
AAPL 2014.04.21D08:00:17.017000000 N   25.33 25.34 9000  2500
AAPL 2014.04.21D08:00:17.634000000 N   25.3  25.36 9500  1000
AAPL 2014.04.21D08:00:19.427000000 L   25.33 25.36 9500  5000
AAPL 2014.04.21D08:00:24.629000000 N   25.33 25.37 6000  2000
AAPL 2014.04.21D08:00:25.207000000 L   25.33 25.36 5000  2500
AAPL 2014.04.21D08:00:29.962000000 L   25.32 25.38 3500  5000
AAPL 2014.04.21D08:00:31.998000000 O   25.34 25.36 5500  4000
AAPL 2014.04.21D08:00:33.795000000 N   25.34 25.36 5000  3500
AAPL 2014.04.21D08:00:34.651000000 L   25.35 25.37 7500  6500
AAPL 2014.04.21D08:00:38.843000000 O   25.33 25.36 4000  6500
AAPL 2014.04.21D08:00:40.062000000 L   25.33 25.38 2000  9500
AAPL 2014.04.21D08:00:43.508000000 N   25.35 25.36 6500  10000
AAPL 2014.04.21D08:00:46.823000000 N   25.35 25.38 6000  7500
..
q)\l .
q)test
sym  time                          src bid   ask   bsize
--------------------------------------------------------
AAPL 2014.04.21D08:00:00.456000000 L   25.32 25.36 8000
AAPL 2014.04.21D08:00:01.387000000 O   25.32 25.35 9500
AAPL 2014.04.21D08:00:10.348000000 N   25.35 25.35 8000
AAPL 2014.04.21D08:00:10.532000000 L   25.33 25.37 5000
AAPL 2014.04.21D08:00:15.163000000 L   25.34 25.36 10000
AAPL 2014.04.21D08:00:15.847000000 N   25.32 25.36 1500
AAPL 2014.04.21D08:00:16.335000000 N   25.33 25.34 8500
AAPL 2014.04.21D08:00:17.017000000 N   25.33 25.34 9000

一旦删除，kdb+将不会将该列与表关联，并且在内存中调用时也不会显示该列

---

希望这有帮助。

是的。还应该补充一点，对于分区表，它必须执行到最后一个分区。这很好。我想我可以在get上运行EXPECT命令，然后删除列，然后设置.d文件。是的。还应该补充一点，对于分区表，它必须执行到最后一个分区。这很好。我想我可以在get上运行except命令，然后删除列，然后再运行set.d文件。