Why doesn't the index be used in my test?

[胡永亮/Bob]

Hi everyone,

    I have a model Kc21, akc273 is its one String column .

    I create the index in this column, as the following:
    @QuerySqlField(index = true)
    private String akc273;

    Then I load data into cache from oracle, total 47535542 rows.

    I execute the sql query to get the execute plan: 
SqlFieldsQuery sql = new SqlFieldsQuery(
  "explain select BKC231 from Kc21 where akc273 = '王妍'");
logger.info("execute plan:"+cache.query(sql).getAll());

    The result is:
    execute plan:[[SELECT
    BKC231 AS __C0
FROM "Kc21Cache".KC21
    /* "Kc21Cache".KC21.__SCAN_ */
WHERE AKC273 = STRINGDECODE('\u738b\u598d')], [SELECT
    __C0 AS BKC231
FROM PUBLIC.__T0
    /* "Kc21Cache"."merge_scan" */]]

    I think this tell me that the index is not used in this sql. Why?
    And the query time also very long as the time before creating this index. 

    Thank your reply. ^V^

    Bob


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