giuseppe guerrini - Page 3

MySQL Server 5.6 defaults changes

- by user12626240

We're improving the MySQL Server defaults, as announced by Tomas Ulin at MySQL Connect. Here's what we're changing: Setting Old New Notes back_log 50 50 + ( max_connections / 5 ) capped at 900 binlog_checksum off CRC32 New variable in 5.6 binlog_row_event_max_size 1k 8k flush_time 1800 Windows changes from 1800 to 0 Was already 0 on other platforms host_cache_size 128 128 + 1 for each of the first 500 max_connections + 1 for every 20 max_connections over 500, capped at 2000 New variable in 5.6 innodb_autoextend_increment 8 64 Now affects *.ibd files. 64 is 64 megabytes innodb_buffer_pool_instances 0 8. On 32 bit Windows only, if innodb_buffer_pool_size is greater than 1300M, default is innodb_buffer_pool_size / 128M innodb_concurrency_tickets 500 5000 innodb_file_per_table off on innodb_log_file_size 5M 48M InnoDB will always change size to match my.cnf value. Also see innodb_log_compressed_pages and binlog_row_image innodb_old_blocks_time 0 1000 1 second innodb_open_files 300 300; if innodb_file_per_table is ON, higher of table_open_cache or 300 innodb_purge_batch_size 20 300 innodb_purge_threads 0 1 innodb_stats_on_metadata on off join_buffer_size 128k 256k max_allowed_packet 1M 4M max_connect_errors 10 100 open_files_limit 0 5000 See note 1 query_cache_size 0 1M query_cache_type on/1 off/0 sort_buffer_size 2M 256k sql_mode none NO_ENGINE_SUBSTITUTION See later post about default my.cnf for STRICT_TRANS_TABLES sync_master_info 0 10000 Recommend: master_info_repository=table sync_relay_log 0 10000 sync_relay_log_info 0 10000 Recommend: relay_log_info_repository=table. Also see Replication Relay and Status Logs table_definition_cache 400 400 + table_open_cache / 2, capped at 2000 table_open_cache 400 2000 Also see table_open_cache_instances thread_cache_size 0 8 + max_connections/100, capped at 100 Note 1: In 5.5 there was already a rule to make open_files_limit 10 + max_connections + table_cache_size * 2 if that was higher than the user-specified value. Now uses the higher of that and (5000 or what you specify). We are also adding a new default my.cnf file and guided instructions on the key settings to adjust. More on this in a later post. We're also providing a page with suggestions for settings to improve backwards compatibility. The old example files like my-huge.cnf are obsolete. Some of the improvements are present from 5.6.6 and the rest are coming. These are ideas, and until they are in an official GA release, they are subject to change. As part of this work I reviewed every old server setting plus many hundreds of emails of feedback and testing results from inside and outside Oracle's MySQL Support team and the many excellent blog entries and comments from others over the years, including from many MySQL Gurus out there, like Baron, Sheeri, Ronald, Schlomi, Giuseppe and Mark Callaghan. With these changes we're trying to make it easier to set up the server by adjusting only a few settings that will cause others to be set. This happens only at server startup and only applies to variables where you haven't set a value. You'll see a similar approach used for the Performance Schema. The Gurus don't need this but for many newcomers the defaults will be very useful. Possibly the most unusual change is the way we vary the setting for innodb_buffer_pool_instances for 32-bit Windows. This is because we've found that DLLs with specified load addresses often fragment the limited four gigabyte 32-bit address space and make it impossible to allocate more than about 1300 megabytes of contiguous address space for the InnoDB buffer pool. The smaller requests for many pools are more likely to succeed. If you change the value of innodb_log_file_size in my.cnf you will see a message like this in the error log file at the next restart, instead of the old error message: [Warning] InnoDB: Resizing redo log from 2*64 to 5*128 pages, LSN=5735153 One of the biggest challenges for the defaults is the millions of installations on a huge range of systems, from point of sale terminals and routers though shared hosting or end user systems and on to major servers with lots of CPU cores, hundreds of gigabytes of RAM and terabytes of fast disk space. Our past defaults were for the smaller systems and these change that to larger shared hosting or shared end user systems, still with a bias towards the smaller end. There is a bias in favour of OLTP workloads, so reporting systems may need more changes. Where there is a conflict between the best settings for benchmarks and normal use, we've favoured production, not benchmarks. We're very interested in your feedback, comments and suggestions.

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How to migrate project from RCS to git? (SOLVED)

- by Norman Ramsey

I have a 20-year-old project that I would like to migrate from RCS to git, without losing the history. All web pages suggest that the One True Path is through CVS. But after an hour of Googling and trying different scripts, I have yet to find anything that successfully converts my RCS project tree to CVS. I'm hoping the good people at Stackoverflow will know what actually works, as opposed to what is claimed to work and doesn't. (I searched Stackoverflow using both the native SO search and a Google search, but if there's a helpful answer in the database, I missed it.) UPDATE: The rcs-fast-export tool at http://git.oblomov.eu/rcs-fast-export was repaired on 14 April 2009, and this version seems to work for me. This tool converts straight to git with no intermediate CVS. Thanks Giuseppe and Jakub!!! Things that did not work that I still remember: The rcs-to-cvs script that ships in the contrib directory of the CVS sources The rcs-fast-export tool at http://git.oblomov.eu/rcs-fast-export in versions before 13 April 2010 The rcs2cvs script found in a document called "CVS-RCS- HOW-TO Document for Linux"

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Remove/squash entries in a vertical hash

- by Forkrul Assail

I have a grid that represents an X, Y matrix, stored as a hash here. Some points on the X Y matrix may have values (as type string), and some may not. A typical grid could look like this: {[9, 5]=>"Alaina", [10, 3]=>"Courtney", [11, 1]=>"Gladys", [8, 7]=>"Alford", [14, 11]=>"Lesley", [17, 2]=>"Lawson", [0, 5]=>"Katrine", [2, 1]=>"Tyra", [3, 3]=>"Fredy", [1, 7]=>"Magnus", [6, 9]=>"Nels", [7, 11]=>"Kylie", [11, 0]=>"Kellen", [10, 2]=>"Johan", [14, 10]=>"Justice", [0, 4]=>"Barton", [2, 0]=>"Charley", [3, 2]=>"Magnolia", [1, 6]=>"Maximo", [7, 10]=>"Olga", [19, 5]=>"Isadore", [16, 3]=>"Delfina", [17, 1]=>"Noe", [20, 11]=>"Francis", [10, 5]=>"Creola", [9, 3]=>"Bulah", [8, 1]=>"Lempi", [11, 7]=>"Raquel", [13, 11]=>"Jace", [1, 5]=>"Garth", [3, 1]=>"Ernest", [2, 3]=>"Malcolm", [0, 7]=>"Alejandrin", [7, 9]=>"Marina", [6, 11]=>"Otilia", [16, 2]=>"Hailey", [20, 10]=>"Brandt", [8, 0]=>"Madeline", [9, 2]=>"Leanne", [13, 10]=>"Jenifer", [1, 4]=>"Humberto", [3, 0]=>"Nicholaus", [2, 2]=>"Nadia", [0, 6]=>"Abigail", [6, 10]=>"Zola", [20, 5]=>"Clementina", [23, 3]=>"Alvah", [19, 11]=>"Wallace", [11, 5]=>"Tracey", [8, 3]=>"Hulda", [9, 1]=>"Jedidiah", [10, 7]=>"Annetta", [12, 11]=>"Nicole", [2, 5]=>"Alison", [0, 1]=>"Wilma", [1, 3]=>"Shana", [3, 7]=>"Judd", [4, 9]=>"Lucio", [5, 11]=>"Hardy", [19, 10]=>"Immanuel", [9, 0]=>"Uriel", [8, 2]=>"Milton", [12, 10]=>"Elody", [5, 10]=>"Alexanne", [1, 2]=>"Lauretta", [0, 0]=>"Louvenia", [2, 4]=>"Adelia", [21, 5]=>"Erling", [18, 11]=>"Corene", [22, 3]=>"Haskell", [11, 11]=>"Leta", [10, 9]=>"Terrence", [14, 1]=>"Giuseppe", [15, 3]=>"Silas", [12, 5]=>"Johnnie", [4, 11]=>"Aurelie", [5, 9]=>"Meggie", [2, 7]=>"Phoebe", [0, 3]=>"Sister", [1, 1]=>"Violet", [3, 5]=>"Lilian", [18, 10]=>"Eusebio", [11, 10]=>"Emma", [15, 2]=>"Theodore", [14, 0]=>"Cassidy", [4, 10]=>"Edmund", [2, 6]=>"Claire", [0, 2]=>"Madisen", [1, 0]=>"Kasey", [3, 4]=>"Elijah", [17, 11]=>"Susana", [20, 1]=>"Nicklaus", [21, 3]=>"Kelsie", [10, 11]=>"Garnett", [11, 9]=>"Emanuel", [15, 1]=>"Louvenia", [14, 3]=>"Otho", [13, 5]=>"Vincenza", [3, 11]=>"Tate", [2, 9]=>"Beau", [5, 7]=>"Jason", [6, 1]=>"Jayde", [7, 3]=>"Lamont", [4, 5]=>"Curt", [17, 10]=>"Mack", [21, 2]=>"Lilyan", [10, 10]=>"Ruthe", [14, 2]=>"Georgianna", [4, 4]=>"Nyasia", [6, 0]=>"Sadie", [16, 11]=>"Emil", [21, 1]=>"Melba", [20, 3]=>"Delia", [3, 10]=>"Rosalee", [2, 8]=>"Myrtle", [7, 2]=>"Rigoberto", [14, 5]=>"Jedidiah", [13, 3]=>"Flavie", [12, 1]=>"Evie", [8, 9]=>"Olaf", [9, 11]=>"Stan", [20, 2]=>"Judge", [5, 5]=>"Cassie", [7, 1]=>"Gracie", [6, 3]=>"Armando", [4, 7]=>"Delia", [3, 9]=>"Marley", [16, 10]=>"Robyn", [2, 11]=>"Richie", [12, 0]=>"Gilberto", [13, 2]=>"Dedrick", [9, 10]=>"Liam", [5, 4]=>"Jabari", [7, 0]=>"Enola", [6, 2]=>"Lela", [3, 8]=>"Jade", [2, 10]=>"Johnson", [15, 5]=>"Willow", [12, 3]=>"Fredrick", [13, 1]=>"Beau", [9, 9]=>"Carlie", [8, 11]=>"Daisha", [6, 5]=>"Declan", [4, 1]=>"Carolina", [5, 3]=>"Cruz", [7, 7]=>"Jaime", [0, 9]=>"Anthony", [1, 11]=>"Esta", [13, 0]=>"Shaina", [12, 2]=>"Alec", [8, 10]=>"Lora", [6, 4]=>"Emely", [4, 0]=>"Rodger", [5, 2]=>"Cedrick", [0, 8]=>"Collin", [1, 10]=>"Armani", [16, 5]=>"Brooks", [19, 3]=>"Eleanora", [18, 1]=>"Alva", [7, 5]=>"Melissa", [5, 1]=>"Tabitha", [4, 3]=>"Aniya", [6, 7]=>"Marc", [1, 9]=>"Marjorie", [0, 11]=>"Arvilla", [19, 2]=>"Adela", [7, 4]=>"Zakary", [5, 0]=>"Emely", [4, 2]=>"Alison", [1, 8]=>"Lorenz", [0, 10]=>"Lisandro", [17, 5]=>"Aylin", [18, 3]=>"Giles", [19, 1]=>"Kyleigh", [8, 5]=>"Mary", [11, 3]=>"Claire", [10, 1]=>"Avis", [9, 7]=>"Manuela", [15, 11]=>"Chesley", [18, 2]=>"Kristopher", [24, 3]=>"Zola", [8, 4]=>"Pietro", [10, 0]=>"Delores", [11, 2]=>"Timmy", [15, 10]=>"Khalil", [18, 5]=>"Trudie", [17, 3]=>"Rafael", [16, 1]=>"Anthony"} What I need to do though, is basically remove all the empty entries. Let's say [17,3] = Raphael does not have an element in front of if (let's say - no [16,3] exists) then [17,3] should become [16,3] etc. So basically all empty items will be popped off the vertical (row) structure of the hash. Are there functions I should have a look at or is there an easy squash-like method that would just remove blanks and adjust and move other items? Thanks in advance for your help.

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