Seaven commented on a change in pull request #2979: Incomplete support Array
type (#2871)
URL: https://github.com/apache/incubator-doris/pull/2979#discussion_r387475124
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File path: be/src/util/mysql_row_buffer.h
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@@ -57,13 +57,44 @@ class MysqlRowBuffer {
int length() const {
return _pos - _buf;
}
+
+ /**
+ * Why?
+ * Because the Nested-Type's data need pushed multiple times, but mysql
protocal don't support nested type and each
+ * push will decide a column data.
+ *
+ * How?
+ * Dynamic mode allow we can push data in a column multiple times, and
allow recursive push.
+ * NOTE:Need to ensure the open() and close() appear in pairs
+ *
+ * the code:
+ * mrb.push_smallint(120);
+ * mrb.push_int(-30000);
+ * mrb.push_bigint(900000);
+ *
+ * In normal mode, the buffer contains three column:
+ * 1-'5'-3-'120'-6-'-30000'
Review comment:
Em......Mysql protocol like this:
```
| flag | (length) | value | flag | (length) | value | ......
^-------A column------^
The flag means value's length or null value:
If value is NULL, flag is 251
If value's length < 250, flag is the value's length
If 250 < value's length < 65536, flag is 252 and the next two byte is length
If 65536 < value's length < 16777216 , flag is 253 and the next three byte
is length
If 16777216 < value's length, flag is 254 and the next eighth byte is length
```
I will update the comment.
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