[jira] [Updated] (SPARK-17074) generate histogram information for column
[ https://issues.apache.org/jira/browse/SPARK-17074?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Zhenhua Wang updated SPARK-17074: - Issue Type: Sub-task (was: Improvement) Parent: SPARK-21975 > generate histogram information for column > - > > Key: SPARK-17074 > URL: https://issues.apache.org/jira/browse/SPARK-17074 > Project: Spark > Issue Type: Sub-task > Components: Optimizer >Affects Versions: 2.0.0 >Reporter: Ron Hu > > We support two kinds of histograms: > - Equi-width histogram: We have a fixed width for each column interval in > the histogram. The height of a histogram represents the frequency for those > column values in a specific interval. For this kind of histogram, its height > varies for different column intervals. We use the equi-width histogram when > the number of distinct values is less than 254. > - Equi-height histogram: For this histogram, the width of column interval > varies. The heights of all column intervals are the same. The equi-height > histogram is effective in handling skewed data distribution. We use the equi- > height histogram when the number of distinct values is equal to or greater > than 254. > We first use [SPARK-18000] to compute equi-width histograms (for both numeric > and string types) or endpoints of equi-height histograms (for numeric type > only). Then, if we get endpoints of a equi-height histogram, we need to > compute ndv's between those endpoints by [SPARK-17997] to form the > equi-height histogram. > This Jira incorporates three Jiras mentioned above to support needed > aggregation functions. We need to resolve them before this one. -- This message was sent by Atlassian JIRA (v6.4.14#64029) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Updated] (SPARK-17074) generate histogram information for column
[ https://issues.apache.org/jira/browse/SPARK-17074?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Zhenhua Wang updated SPARK-17074: - Issue Type: Improvement (was: Sub-task) Parent: (was: SPARK-16026) > generate histogram information for column > - > > Key: SPARK-17074 > URL: https://issues.apache.org/jira/browse/SPARK-17074 > Project: Spark > Issue Type: Improvement > Components: Optimizer >Affects Versions: 2.0.0 >Reporter: Ron Hu > > We support two kinds of histograms: > - Equi-width histogram: We have a fixed width for each column interval in > the histogram. The height of a histogram represents the frequency for those > column values in a specific interval. For this kind of histogram, its height > varies for different column intervals. We use the equi-width histogram when > the number of distinct values is less than 254. > - Equi-height histogram: For this histogram, the width of column interval > varies. The heights of all column intervals are the same. The equi-height > histogram is effective in handling skewed data distribution. We use the equi- > height histogram when the number of distinct values is equal to or greater > than 254. > We first use [SPARK-18000] to compute equi-width histograms (for both numeric > and string types) or endpoints of equi-height histograms (for numeric type > only). Then, if we get endpoints of a equi-height histogram, we need to > compute ndv's between those endpoints by [SPARK-17997] to form the > equi-height histogram. > This Jira incorporates three Jiras mentioned above to support needed > aggregation functions. We need to resolve them before this one. -- This message was sent by Atlassian JIRA (v6.4.14#64029) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Updated] (SPARK-17074) generate histogram information for column
[ https://issues.apache.org/jira/browse/SPARK-17074?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Zhenhua Wang updated SPARK-17074: - Description: We support two kinds of histograms: - Equi-width histogram: We have a fixed width for each column interval in the histogram. The height of a histogram represents the frequency for those column values in a specific interval. For this kind of histogram, its height varies for different column intervals. We use the equi-width histogram when the number of distinct values is less than 254. - Equi-height histogram: For this histogram, the width of column interval varies. The heights of all column intervals are the same. The equi-height histogram is effective in handling skewed data distribution. We use the equi- height histogram when the number of distinct values is equal to or greater than 254. We first use [SPARK-18000] to compute equi-width histograms (for both numeric and string types) or endpoints of equi-height histograms (for numeric type only). Then, if we get endpoints of a equi-height histogram, we need to compute ndv's between those endpoints by [SPARK-17997] to form the equi-height histogram. This Jira incorporates three Jiras mentioned above to support needed aggregation functions. We need to resolve them before this one. was: We support two kinds of histograms: - Equi-width histogram: We have a fixed width for each column interval in the histogram. The height of a histogram represents the frequency for those column values in a specific interval. For this kind of histogram, its height varies for different column intervals. We use the equi-width histogram when the number of distinct values is less than 254. - Equi-height histogram: For this histogram, the width of column interval varies. The heights of all column intervals are the same. The equi-height histogram is effective in handling skewed data distribution. We use the equi- height histogram when the number of distinct values is equal to or greater than 254. We first use [SPARK-18000] and [SPARK-17881] to compute equi-width histograms (for both numeric and string types) or endpoints of equi-height histograms (for numeric type only). Then, if we get endpoints of a equi-height histogram, we need to compute ndv's between those endpoints by [SPARK-17997] to form the equi-height histogram. This Jira incorporates three Jiras mentioned above to support needed aggregation functions. We need to resolve them before this one. > generate histogram information for column > - > > Key: SPARK-17074 > URL: https://issues.apache.org/jira/browse/SPARK-17074 > Project: Spark > Issue Type: Sub-task > Components: Optimizer >Affects Versions: 2.0.0 >Reporter: Ron Hu > > We support two kinds of histograms: > - Equi-width histogram: We have a fixed width for each column interval in > the histogram. The height of a histogram represents the frequency for those > column values in a specific interval. For this kind of histogram, its height > varies for different column intervals. We use the equi-width histogram when > the number of distinct values is less than 254. > - Equi-height histogram: For this histogram, the width of column interval > varies. The heights of all column intervals are the same. The equi-height > histogram is effective in handling skewed data distribution. We use the equi- > height histogram when the number of distinct values is equal to or greater > than 254. > We first use [SPARK-18000] to compute equi-width histograms (for both numeric > and string types) or endpoints of equi-height histograms (for numeric type > only). Then, if we get endpoints of a equi-height histogram, we need to > compute ndv's between those endpoints by [SPARK-17997] to form the > equi-height histogram. > This Jira incorporates three Jiras mentioned above to support needed > aggregation functions. We need to resolve them before this one. -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Updated] (SPARK-17074) generate histogram information for column
[ https://issues.apache.org/jira/browse/SPARK-17074?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Zhenhua Wang updated SPARK-17074: - Description: We support two kinds of histograms: - Equi-width histogram: We have a fixed width for each column interval in the histogram. The height of a histogram represents the frequency for those column values in a specific interval. For this kind of histogram, its height varies for different column intervals. We use the equi-width histogram when the number of distinct values is less than 254. - Equi-height histogram: For this histogram, the width of column interval varies. The heights of all column intervals are the same. The equi-height histogram is effective in handling skewed data distribution. We use the equi- height histogram when the number of distinct values is equal to or greater than 254. We first use [SPARK-18000] and [SPARK-17881] to compute equi-width histograms (for both numeric and string types) or endpoints of equi-height histograms (for numeric type only). Then, if we get endpoints of a equi-height histogram, we need to compute ndv's between those endpoints by [SPARK-17997] to form the equi-height histogram. This Jira incorporates three Jiras mentioned above to support needed aggregation functions. We need to resolve them before this one. was: We support two kinds of histograms: - Equi-width histogram: We have a fixed width for each column interval in the histogram. The height of a histogram represents the frequency for those column values in a specific interval. For this kind of histogram, its height varies for different column intervals. We use the equi-width histogram when the number of distinct values is less than 254. - Equi-height histogram: For this histogram, the width of column interval varies. The heights of all column intervals are the same. The equi-height histogram is effective in handling skewed data distribution. We use the equi- height histogram when the number of distinct values is equal to or greater than 254. > generate histogram information for column > - > > Key: SPARK-17074 > URL: https://issues.apache.org/jira/browse/SPARK-17074 > Project: Spark > Issue Type: Sub-task > Components: Optimizer >Affects Versions: 2.0.0 >Reporter: Ron Hu > > We support two kinds of histograms: > - Equi-width histogram: We have a fixed width for each column interval in > the histogram. The height of a histogram represents the frequency for those > column values in a specific interval. For this kind of histogram, its height > varies for different column intervals. We use the equi-width histogram when > the number of distinct values is less than 254. > - Equi-height histogram: For this histogram, the width of column interval > varies. The heights of all column intervals are the same. The equi-height > histogram is effective in handling skewed data distribution. We use the equi- > height histogram when the number of distinct values is equal to or greater > than 254. > We first use [SPARK-18000] and [SPARK-17881] to compute equi-width histograms > (for both numeric and string types) or endpoints of equi-height histograms > (for numeric type only). Then, if we get endpoints of a equi-height > histogram, we need to compute ndv's between those endpoints by [SPARK-17997] > to form the equi-height histogram. > This Jira incorporates three Jiras mentioned above to support needed > aggregation functions. We need to resolve them before this one. -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
