Louay Kamel created CASSANDRA-15096: ---------------------------------------
Summary: [RFC CQL v4+] cql_extension: wide range of unset_values. Key: CASSANDRA-15096 URL: https://issues.apache.org/jira/browse/CASSANDRA-15096 Project: Cassandra Issue Type: Improvement Components: CQL/Interpreter, CQL/Semantics Reporter: Louay Kamel *# Problem* The current implementation of unset_value regularly fails (see Issues). We need to implement a new unset_value(s) mechanism which is robust and will work well for v4+ protocols. *# Issues* +1- A client has to encode unset_value for all the columns+ +in an insert-prepared query values.+ example: INSERT INTO table(pkey,ckey,col1,col2,col3,col4) values(?,?,?,?,?,?); An execute query should unset all the columns one by one by encoding unset_value as "int(-2)" a- binded-values = (pkey_value, ckey_value, col1_value, unset_value, unset_value, unset_value) or b- binded-values = (pkey_value, ckey_value, unset_value, unset_value, unset_value, col4_value) etc. this increase the execute query binary buffer which is in term increase the bandwidth and latency for both request/response. +2- Returning Select-queries buffer not differentiate between null and unset_value for a subset of given rows.+ example: imagine you have a dataset in the table where each row of the returning select response have different unset/null columns, consider the following query: SELECT * FROM table where pkey = pkey_value; and with a page_size = 3 rows , row1 -> pkey_value, ckey_value, col1_value, null/unset_value, null/unset_value, null/unset_value. row2 -> pkey_value, ckey_value, null/unset_value, null/unset_value, null/unset_value, col4_value. row3 -> pkey_value, ckey_value, null/unset_value, null/unset_value, col3_value, null/unset_value. *# Proposed solution* Instead of just having null(-1) and unset_value(-2), extending the unset_value(s) to a range from unset_(-2) to unset_(-2,147,483,648), where unset_value = unset_(-2) unset_rest = unset_(-2,147,483,648) anything in between will be unset_(neg_integer). +Solution for issue_1:+ a- binded-values = (pkey_value, ckey_value, col1_value, unset_rest) b- binded-values = (pkey_value, ckey_value, unset_(-4), col4_value) +Solution for issue_2:+ work with all select-un/prepared responses. row1 buffer -> pkey_value, ckey_value, col1_value, unset_rest. this will enable the buffer to shift to a new row. row2 buffer -> pkey_value, ckey_value, unset_(-4), col4_value. this will enable the buffer to skip the columns metadata -4+1=-3 columns and start decoding from col4 for the next cell_value in the row. row3 buffer -> pkey_value, ckey_value, unset_(-3), col3_value, unset_rest. this buffer is a mix of row1/row2. this solution not limited to unset_(neg-int) , it can be used on null cell responses to decrease the bandwidth between CQL and client. to be compatible with all the current v4+ cql/drivers, we should force the client to send a flag with the select query request (either in the frame-header or somewhere in the cql statement), and for returning buffer we could use the rows flags (ex, has_unset_values?: boolean) to let the driver know if it exist in the page. *# Benefits* -implementing this will enable apps to design complex data-model up to 2 billion columns without trading off anything. -reducing the number of write-prepared statements in datamodel with millions of columns to a highest degree. -huge impact on the bandwidth/cpu-cycles. -easy to implement in the client side. # Record of votes +1 Louay Kamel -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org