#6) Master and slave are connected using synchronous replication. Asynchronous replication#have slight (almost none) chance to bring total cluster into inconsistent state.#This chance is very low and may be negligible. Support of asynchronous replication#may be supported in the later release.# #7)...
所以我知道,如果我使用一个带有日期序列的列的表,并将第一个数据表连接起来,就像用婴儿步骤来测试我的理论一样: SELECT date_table.date_list, sums_1.sum FROM date_table FULL OUTER JOIN sums_1 ON date_table.date_list = sums_1.date_list 2020-03-07 | 1 2020-03-08 | 2020-03-09 | 2020-0...
"description: "Name of current database"- schemaname:usage: "LABEL"description: "Name of the schema that this table is in"- relname:usage: "LABEL"description: "Name of this table"- seq_scan:usage: "COUNTER"description: "Number of sequential scans initiated on this table"- seq_tup_read:...
TupleTableSlot *ExecSort(SortState *node) 它被上层的ExecProcNode函数调用,输出元组。 在ExecSort函数的首次调用中会首先通过tuplesort_begin_heap对元组缓存结构初始化,返回一个Tuplesortstate结构。 Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc,intnkeys, AttrNumber *attNums, ...
But it's typically cheaper to just catch that error and retry in those very rare cases instead of locking the whole table (you cannot lock rows that don't exist yet in Postgres) or locking all rows for the given user exclusively. You could wrap the INSERT in a PL/pgSQL function to ...
一、特性postgres分区表是数据层层面的, 相对于普通表在内部实现复杂,但是用户无感知.分区表是一种将大表拆分成多个小表的方式Hash 分区:根据特定列的哈希值将数据均匀分布到多个分区中。...Range分区: 表被分区为由分区键定义的“范围”,分配给不同分区的值范围之间没有
until an equally expensive vacuum runs through and frees space, and only when it's allowed to after rows are no longer visible to any other query in the system, whether they're making use of the large table or not. Each row removal land in the WAL, resulting in significant amplification...
At the end, it estimates the total number of live tuples based on the number of pages and tuples scanned (in the same way that VACUUM estimates pg_class.reltuples). Possible example: SELECT * FROM pgstattuple_approx('<schema_name>.<table_name>::regclass); Possible results: -[ RECORD...
typedef struct { void *tuple; /* the tuple itself */ Datum datum1; /* value of first key column */ bool isnull1; /* is first key column NULL? */ int srctape; /* source tape number */ --归并阶段用到,记录了出堆的元组是从哪个tape读取的 } SortTuple; 当内存中无法再存放元组时,...
(attnum < 0); /* caller error */ if (attnum == TableOidAttributeNumber) { *isnull = false; return ObjectIdGetDatum(slot->tts_tableOid); } else if (attnum == SelfItemPointerAttributeNumber) { *isnull = false; return PointerGetDatum(&slot->tts_tid); } /* Fetch the system ...