google-cloud-spanner

来源： https://stackoverflow.com/questions/60075381/using-multiple-count-distinct-has-huge-performance-impact

问题 In the doc we can find a query hint named USE_ADDITIONAL_PARALLELISM here: https://cloud.google.com/spanner/docs/query-syntax#statement-hints However the documentation is very short for it. From my understanding it will spread a single query to be executed on multiple nodes. Is that correct? In what scenario would we use it? What is its impact on the infrastructure? How does it scale with number of nodes? Does it need a query that picks data from different splits, or does it work on a single

问题 I have few spanner tables where I'm facing latency issue while fetching rows through API's. So we are using secondary index for multiple tables, as it improves the performance. We are using around 50 spanner nodes and average utilisation is around 60% and the query being performed are on top of secondary index. Spanner table has 16 secondary index. With all this functionality on place, we are still facing latency issue as query took around 37 seconds to complete. Query is not the complicated

问题 I have few spanner tables where I'm facing latency issue while fetching rows through API's. So we are using secondary index for multiple tables, as it improves the performance. We are using around 50 spanner nodes and average utilisation is around 60% and the query being performed are on top of secondary index. Spanner table has 16 secondary index. With all this functionality on place, we are still facing latency issue as query took around 37 seconds to complete. Query is not the complicated

问题 I have few spanner tables where I'm facing latency issue while fetching rows through API's. So we are using secondary index for multiple tables, as it improves the performance. We are using around 50 spanner nodes and average utilisation is around 60% and the query being performed are on top of secondary index. Spanner table has 16 secondary index. With all this functionality on place, we are still facing latency issue as query took around 37 seconds to complete. Query is not the complicated

问题 I am going to create batch for GCP spanner am planning to use JdbcCursorItemReader that needs datasource, So i need to create datasource for my GCP Spanner instance, Can you please suggest me on this? 回答1: You need to add the Cloud Spanner JDBC driver to your build path like this: <dependency> <groupId>com.google.cloud</groupId> <artifactId>google-cloud-spanner-jdbc</artifactId> <version>1.9.0</version> </dependency> Then you can define a Spring data source in the normal way. Doing it

问题 I am going to create batch for GCP spanner am planning to use JdbcCursorItemReader that needs datasource, So i need to create datasource for my GCP Spanner instance, Can you please suggest me on this? 回答1: You need to add the Cloud Spanner JDBC driver to your build path like this: <dependency> <groupId>com.google.cloud</groupId> <artifactId>google-cloud-spanner-jdbc</artifactId> <version>1.9.0</version> </dependency> Then you can define a Spring data source in the normal way. Doing it

问题 I have a use case where I need to migrate 70 TB of data from DynamoDB to BigTable and Spanner. Tables with a single index will go to BigTable else they will go to Spanner. I can easily handle the historical loads by exporting the data to S3 --> GCS --> Spanner/BigTable. But the challenging part is to handle the incremental streaming loads simultaneously happening on DynamoDB. There are 300 tables in DynamoDB. How to handle this thing in the best possible manner? Has anyone done this before?

问题 I tried to read the document multiple times but failed to understand it. Can someone explain it in layman's terms? 回答1: TrueTime is an API available at Google that directly exposes clock uncertainty. Comparing to standard datetime libraries, instead of a particular timestamp, TrueTime's now() function returns an interval of time [earliest, latest]. It also provides two functions: after(t) returns true if t has definitely passed. E.g. t < now().earliest . before(t) returns true if t has

问题 I tried to read the document multiple times but failed to understand it. Can someone explain it in layman's terms? 回答1: TrueTime is an API available at Google that directly exposes clock uncertainty. Comparing to standard datetime libraries, instead of a particular timestamp, TrueTime's now() function returns an interval of time [earliest, latest]. It also provides two functions: after(t) returns true if t has definitely passed. E.g. t < now().earliest . before(t) returns true if t has