真实案例的情况是:SQL正常执行时间3.4分钟,某天TV表delete一些记录后,执行了将近20分钟还没有完成,而其中最重要的变化就是执行计划其中的一个hash join变成了nested loops,虽然hint中已经指定全部表要use_hash。 这个模拟的SQL展示的就是真实案例出现异常的情况。其中一个步骤使用了nested loops,大概要执行4分钟左右才...
Using USE_HASH hint I resolved network bottleneck as much less data was being sent over the network. My colleague was very pleased with query performance improvement :)
三、USE_HASH(哈希连接) 当内存能够提供足够的空间时,哈希(HASH)连接是Oracle优化器通常的选择。在哈希连接中,Oracle访问一张表(通常是较大的表),并在内存中建立一张基于连接键的哈希表。然后它扫描连接中其他的表(通常是较大的表),并根据哈希表检测是否有匹配的记录。 只有在数据库初始化参数HASH_JOIN_ENABLED...
指定agg算法的Hint 功能描述 在进行agg算法时可以指定agg的方法。 语法格式use_hash_agg[(@queryblock)],use_sort_agg[(@queryblock)] 参数说明 @queryblock请参见指定Hint所处于的查询块Querybl 来自:帮助中心 查看更多 → 存储过程支持自治事务 PROCEDURE --调用普通存储过程 gaussdb=# SELECT autonomous_5(11...
CREATETABLEt(atextcollate"C",btextcollatecase_insensitive);INSERTINTOtVALUES('Hello','world');——计算ifnull(a,b)的值的哈希值SELECThashtext(ifnull(a,b))FROMt;ERROR:dn_6005_6006:couldnotdeterminewhichcollationtouseforstringhashing.HINT:UsetheCOLLATEclausetosetthecollationexplicitly. ...
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I see no hint message from the output or doc. There is a sklearn.cluster.HDBSCAN, and I find sklearn is already there with funasr installed. Can we just use that sklearn one instead of installing the standalone version hdbscan? These two versions seem coming from same authors, and ...
Map<String, Object> valueMap = new HashMap<String, Object>(1); valueMap.put(myValueAttrCode, "N"); combAttrs.setValueAttributes(myLabel, valueMap); System.out.println(); /*** Dealing with standard value attributes. ***/ // Get the segment values with the standard value attributes. ...
Sukhraj continues, “Instagram only gives you 150 characters in your bio. Use them to tell people why they should follow you. Include who you are and what you do, but also a hint of personality.” Add a Website Adding your online presence to your Instagram page, like your website or ...
Using the USE PLAN Query Hint Using the USE PLAN Query Hint on Queries with Cursors Plan Forcing Scenarios and Examples Finding and Tuning Similar Queries by Using Query and Query Plan Hashes Optimizing Queries That Access Correlated datetime Columns Using the FORCESEEK Table Hint Optimizing MERGE ...