tombstone | 易学教程

Does Cassandra Insert JSON creates Tombstones?

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问题 I am using Cassandra's insert JSON feature to insert data into the table. In the JSON that I create, I do not include the null values. Meaning, ignore the fields that have null values in it. Does Cassandra create tombstones in such cases, if I am inserting the record say, for the first time? I assume for subsequent upsert for the same key will create tombstone. Is that right? 回答1: Cell tombstone should still get created for the values which are not included in the json you are trying to

Backstack Tombstone wp7

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问题 I have just finished tombstoning a page in my application when I noticed that I only tombstone the page I am currently viewing, meaning that after I return the pages in the backstack lose all their members and doesn't get tombstoned.. I only find examples on how to tomstone the current page but nothing about tombstoning the backstack pages... What is the elegant way to do this? Just to show How I'm tombstoning: protected override void OnNavigatedTo(NavigationEventArgs e) { if (e

Is it possible to avoid tombstone problems with Cassandra?

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问题 I am writing code for a CMS using Cassandra as the database system. One of the strength of the CMS is to pre-calculate all sorts of things using a backend computer that permanently runs against data that changes in the CMS. For example, the CMS tells the list system that a page was created or changed. The list system saves that information in a table called list . That information is just a one liner which tells me which page has to be worked on. Column family: list Row: concerned website (i

Inserting null values into cassandra

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问题 I have some fields that I am storing into Cassandra, but some of them could be null at any given point. As there are quite a lot of them, it makes the code much more readable if I don’t check each one for null before adding it to the INSERT. Is there any harm in doing so? EDIT!! There is a jira ticket that I found. But I am unable to understand what solution was finally implemented from the ticket. https://issues.apache.org/jira/browse/CASSANDRA-7304 回答1: The beautiful thing about Cassandra's

how to access android files /data/anr/traces.txt and /data/tombstones/tombstones [duplicate]

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问题 This question already has answers here : Android: How to obtain data/anr/traces.txt from Samsung Galaxy Tab? (4 answers) Closed 11 months ago . I am writing an application for reporting crashes and the relevant logs. So from my application I am trying to access traces.txt and tombstones, but I am getting an error: 03-25 09:48:46.220 W/System.err(10250): java.io.FileNotFoundException: /data/tombstone/tombstone_00 (Permission denied) I am able to access traces.txt , but not tombstones. 回答1: You

how to access android files /data/anr/traces.txt and /data/tombstones/tombstones [duplicate]

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Cassandra and Tombstones: Creating a Row , Deleting the Row, Recreating the Row = Performance?

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问题 Could someone please explain, what effect the following process has on tombstones: 1.)Creating a "Row" with Key "1" ("Fields": user, password, date) 2.)Deleting the "Row" with Key "1" 3.)Creating a "Row" with Key "1" ("Fields": user, password,logincount) The sequence is executed in one thread sequentially (so this happens with a relatively high "speed" = no long pauses between the actions). My Questions: 1.) What effect does this have on the creation of a tombstone. After 2.) a tombstone is

Cassandra and Tombstones: Creating a Row , Deleting the Row, Recreating the Row = Performance?

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Could someone please explain, what effect the following process has on tombstones: 1.)Creating a "Row" with Key "1" ("Fields": user, password, date) 2.)Deleting the "Row" with Key "1" 3.)Creating a "Row" with Key "1" ("Fields": user, password,logincount) The sequence is executed in one thread sequentially (so this happens with a relatively high "speed" = no long pauses between the actions). My Questions: 1.) What effect does this have on the creation of a tombstone. After 2.) a tombstone is created/exists. But what happens to the existing tombstone, if the new (slightly changed row) is created

Overwrite row in cassandra with INSERT, will it cause tombstone?

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问题 Writing data to Cassandra without causing it to create tombstones are vital in our case, due to the amount of data and speed. Currently we have only written a row once, and then never had the need to update the row again, only fetch the data again. Now there has been a case, where we actually need to write data, and then complete it with more data, that is finished after awhile. It can be made by either; overwrite all of the data in a row again using INSERT (all data is available), or

Can I force cleanup of old tombstones?

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问题 I have recently lowered gc_grace_seconds for a CQL table. I am running LeveledCompactionStrategy . Is it possible for me to force purging of old tombstones from my SSTables? 回答1: TL;DR Your tombstones will disappear on their own through compaction bit make sure you are running repair or they may come back from the dead. http://www.datastax.com/documentation/cassandra/2.0/cassandra/dml/dml_about_deletes_c.html Adding some more details: Tombstones are not immediately available for deletion