update statistics

update statistics 是 SQL Server 中的一条命令，它用于更新数据表的统计信息，以便查询优化器可以更好地评估和选择执行计划。当 SQL Server 查询优化器需要为一个查询编制执行计划时，它会使用表的统计信息来预测查询的行数、数据分布和数据分页等信息，然后选择最优的执行计划。

update statistics 命令可以手动更新指定表的统计信息，以便保证查询优化器使用最新的信息进行查询优化和执行计划选择。可以使用 WITH FULLSCAN 选项更新所有行的统计信息，或者使用 WITH SAMPLE 选项更新部分行的统计信息。

需要注意的是，update statistics 命令可能会引起锁冲突和性能问题，因此在生产环境中应该谨慎使用，并在非高峰期进行操作。

相关问题

insert into marketing_statistics_order100470 values(xxxxxxxxxxxxxx) on conflict(id) do update set xxxxxxxxxxxxx

这是一个PostgreSQL SQL语句，用于在`marketing_statistics_order100470`表中插入数据，并在遇到id冲突（即尝试插入的id已存在）时执行更新操作。具体解释如下：

`INSERT INTO marketing_statistics_order100470 VALUES (xxxxxxxxxxxxx)`:
这部分是插入语句，`(xxxxxxxxxxxxx)`是要插入的具体记录值，这里的每个字段值应替换为实际的值。

`ON CONFLICT(id) DO UPDATE SET xxxxxxxxxxxxx`:
这部分是解决冲突的部分：
- `ON CONFLICT(id)`：指定冲突条件，这里是基于`id`字段冲突。如果有两条记录的`id`字段相同，就会发生冲突。
- `DO UPDATE`：表明当冲突发生时，会执行更新操作。
- `SET xxxxxxxxxxxxx`：在这里，你需要提供新的值来更新哪些字段，如`new_column_name = 'new_value'`。你需要将`xxxxxxxxxx`替换为实际要更新的列名和新值。

举个例子，如果`product_id`是你想要更新的冲突字段，并希望在冲突时更新价格`price`，完整的语句可能是这样的：

INSERT INTO marketing_statistics_order100470 (product_id, price)
VALUES ('your_product_id', 'your_new_price')
ON CONFLICT (product_id) DO UPDATE SET price = EXCLUDED.price;

这里假设`EXCLUDED.price`表示插入的新值，如果没有明确指定，则默认使用`VALUES`里的对应值。

[0710/081418.767757] [INFO:main.cc(55)] A/B Update Engine starting [0710/081418.775873] [INFO:boot_control_android.cc(69)] Loaded boot control hidl hal. [0710/081418.844522] [ERROR:update_attempter_android.cc(936)] prefs_->GetInt64(kPrefsPreviousSlot, &previous_slot) failed. [0710/081418.850761] [INFO:update_attempter_android.cc(196)] OTAResult::NOT_ATTEMPTED [0710/081418.883202] [INFO:update_attempter_android.cc(1262)] Scheduling CleanupPreviousUpdateAction. [0710/081418.895190] [INFO:action_processor.cc(51)] ActionProcessor: starting CleanupPreviousUpdateAction [0710/081418.899394] [INFO:cleanup_previous_update_action.cc(149)] Starting/resuming CleanupPreviousUpdateAction [0710/081418.902350] [INFO:cleanup_previous_update_action.cc(124)] CleanupPreviousUpdateAction scheduled task ID 1 for WaitBootCompleted [0710/081420.904474] [INFO:cleanup_previous_update_action.cc(112)] Executing task 1 [0710/081420.906355] [INFO:cleanup_previous_update_action.cc(124)] CleanupPreviousUpdateAction scheduled task ID 3 for WaitBootCompleted [0710/081422.908519] [INFO:cleanup_previous_update_action.cc(112)] Executing task 3 [0710/081422.910627] [INFO:cleanup_previous_update_action.cc(124)] CleanupPreviousUpdateAction scheduled task ID 4 for WaitBootCompleted [0710/081424.915286] [INFO:cleanup_previous_update_action.cc(112)] Executing task 4 [0710/081424.919637] [INFO:cleanup_previous_update_action.cc(124)] CleanupPreviousUpdateAction scheduled task ID 5 for WaitBootCompleted [0710/081426.923179] [INFO:cleanup_previous_update_action.cc(112)] Executing task 5 [0710/081426.927580] [INFO:cleanup_previous_update_action.cc(124)] CleanupPreviousUpdateAction scheduled task ID 6 for WaitBootCompleted [0710/081428.930648] [INFO:cleanup_previous_update_action.cc(112)] Executing task 6 [0710/081428.936232] [INFO:cleanup_previous_update_action.cc(124)] CleanupPreviousUpdateAction scheduled task ID 7 for WaitBootCompleted [0710/081430.938563] [INFO:cleanup_previous_update_action.cc(112)] Executing task 7 [0710/081430.943791] [INFO:cleanup_previous_update_action.cc(189)] Boot completed, waiting on markBootSuccessful() [0710/081430.947213] [INFO:snapshot.cpp(3766)] EnsureMetadataMounted does nothing in Android mode. [0710/081430.950810] [INFO:snapshot_stats.cpp(37)] Read merge statistics file failed: No such file or directory [0710/081430.965136] [INFO:cleanup_previous_update_action.cc(261)] Waiting for any previous merge request to complete. This can take up to several minutes. [0710/081430.974341] [INFO:snapshot.cpp(1047)] CheckMergeState for snapshots returned: 0 [0710/081430.981751] [INFO:snapshot.cpp(1019)] ProcessUpdateState handling state: 0 [0710/081430.988898] [INFO:cleanup_previous_update_action.cc(297)] Can't find any snapshot to merge. [0710/081430.996749] [INFO:cleanup_previous_update_action.cc(130)] Stopping/suspending/completing CleanupPreviousUpdateAction [0710/081431.002327] [INFO:cleanup_previous_update_action.cc(479)] Not reporting merge stats because state is None [0710/081431.014705] [INFO:cleanup_previous_update_action.cc(130)] Stopping/suspending/completing CleanupPreviousUpdateAction [0710/081431.022443] [INFO:action_processor.cc(116)] ActionProcessor: finished last action CleanupPreviousUpdateAction with code ErrorCode::kSuccess [0710/081431.031005] [INFO:update_attempter_android.cc(570)] Processing Done. [0710/081431.038024] [INFO:update_attempter_android.cc(826)] Clearing update complete marker. [0710/081431.046821] [INFO:update_attempter_android.cc(722)] Terminating cleanup previous update. 什么意思？

这段日志是关于一个名为 "CleanupPreviousUpdateAction" 的操作的记录。根据日志，它是在 Android 系统中执行的，目的是清理之前的更新操作。

具体来说，日志中显示了一系列任务被执行，这些任务被安排在启动完成后执行。任务的目标是等待系统启动完成，并在特定任务执行之前执行清理操作。

但是，在这个日志中，没有找到任何需要合并的快照（snapshot），因此没有进行任何合并操作。

最后，日志显示 "CleanupPreviousUpdateAction" 操作已经完成，并以成功的状态结束。

所以，总的来说，这段日志是关于清理之前更新操作的记录，并且没有进行任何合并操作。