如:SELECT ID FROM T WHERE NUM IN(1,2,3) 对于连续的数值,能用 BETWEEN就不要用 IN了,如:SELECT ID FROM T WHERE NUM BETWEEN 1 AND 3。 7、尽量避免在索引过的字符数据中,使用非打头字母搜索。这也使得引擎无法利用索引。 见如下例子:SELECT * FROM T1 WHERE NAME LIKE '%L%' ---> 无索引 SEL...
dateStr=\$(date -d '+1 days' +%Y%m%d); psql -c "CREATE TABLE tab_\$dateStr (LIKE tab INCLUDING INDEXES); ALTER TABLE tab ATTACH PARTITION tab_\$dateStr FOR VALUES IN ('\$dateStr')"; EOF (crontab -l2>/dev/null;echo"0 14 * * * bash /tmp/create_part.sh ")|crontab- 使用...
建议放/etc/profile里面。后面还要创建postgresql用户组。And to enable your system to find the man documentation, you need to add lines like the following to a shell start-up file unless you installed into a location that is searched by default: ...
LIKE条件与WHERE子句一起用于从指定条件满足LIKE条件的表中获取数据 语法: SELECTcolumn1,column2,...columnNFROMtable_nameWHERE[search_condition]LIKE[condition]; 示例1: select*fromemployeeswherenamelike'Ma%'; 结果1: 示例2: select*fromemployeeswhereaddresslike'%大道%'; 结果2: 3.5 IN条件 说明: IN条...
* laid out in such a way as to avoid structure padding. * ... * The overall structure of a heap tuple looks like: * fixed fields (HeapTupleHeaderData struct) * nulls bitmap (if HEAP_HASNULL is set in t_infomask) * alignment padding (as needed to make user data MAXALIGN'd) ...
typedefstructAllocSetContext{MemoryContextData header;/*对应于该内存上下文的头部信息 Standard memory-context fields *//* Info about storage allocated in this context: */AllocBlock blocks;/*该内存上下文中所有内存块的链表 head of list of blocks in this set */AllocChunk freelist[ALLOCSET_NUM_FREEL...
# <Compat> # Alow users to use the old style arguments like # 'postgresql-setup initdb $SERVICE_NAME'.case "$1" in initdb|upgrade) action="--$1" shift warn "using obsoleted argument syntax, try --help" old_long_args="help,usage,version,debug" ...
仅支持在Range或List分区列上使用范围、等式和IN列表谓词。AnalyticDB PostgreSQL 7.0版支持Hash分区,Hash分区只能通过等值条件进行裁剪。 动态分区裁剪仅支持分区列的等值条件,如=或IN等。 分区裁剪效果与数据分布有关,如果分区约束无法有效裁剪,性能会回退到与全表扫描一致。
for i in 0..parts-1 loopexecuteformat('create table tbl%s (like tbl including all) inherits (tbl)', i);executeformat('alter table tbl%saddconstraint ck check(mod(id,%s)=%s)', i, parts, i); end loop; end; $$; 3、创建触发器函数,内容为数据路由,路由后返回NULL(即不写本地父表) ...
SELECT device_id, event_time, data->>'measurement' AS value, device_name, device_type_name FROM events JOIN devices USING (device_id) JOIN device_types USING (device_type_id) WHERE device_type_name LIKE 'laptop%' ORDER BY event_time DESC LIMIT 3; device_id | event_time | value | ...