[[TOC]] This page describes two tools which are - apart from their input file format - nearly identical: `root2sql` and `fits2sql`. == Purpose == Both file types, ROOT and FITS files, have storage engines for the storage of table like data. In ROOT files these are trees with branches and leaves and in FITS files these are FITS tables, the so-called ''extensions''. Although, ''root'' offers a lot of printing and fitting options, sometimes the access through a database has advantages. Therefore, a tool which maps ROOT-files and FITS-files into SQL tables helps. == Introduction == First get the man page of `root2sql` either with `root2sql --help` or (if installed) with `man root2sql`. This page will mainly outline how `root2sql` works, because `fits2sql` is slightly less complex. In short, the differences will be explained at the end of the document. == Connection == How a connection to the database is established is outlined in: DatabaseBasedAnalysis/Connection. Per default, your connection will be compressed if the the host-address of the mysql-server is neither '''localhost''' nor '''127.0.0.1'''. To force compression use {{{ uri fact:password@ihp-pc45.ethz.ch/factdata?compress=1 }}} Generally, compression should be enable if connecting from the world. To test compression, the "''Hello World! ''" example can be used. In the following it is assumed that the database connection is working and tested, so that the resources ({{{uri=...}}}) are omitted. == Basics == Generally, ROOT-files can store very complicated object as a TH1F. Although, they could be entered in a database as a so called BLOB (a binary object), this is not the idea of the tool. Thus only basic data types are supported. == Input == The input file is given as the first positional argument {{{ root2sql [--file] inputfile.root }}} Each root tree has branches and leaves (the basic data types). These leaves can be read independently of the classes which were used to write the root file. The default tree to read from is '''Events''' but the name can be overwritten using `-t` (an abbreviation of `--tree`). Which would look like this {{{ root2sql inputfile.root -t MyTree }}} == Output == === Table Name === The default table which is filled with the data in this tree is expected to have the same name than the tree. If this is not the case, it can be changed with `--table`. {{{ root2sql inputfile.root -t MyTree --table MyTable }}} In these three examples, the first one would read from a tree ''Events'' and write to table ''Events''. The second case would read from a tree ''MyTree'' and write to a table ''MyTree'' and the third case would read from a tree ''MyTree'' and write to a table ''MyTable''. === Column Names === The name of each column to which data is filled from a leave is obtained from the leaves' names. The leave names can be checked using `--print-leaves`. A `--print-branches` exists for convenience to print only the high-level branches. If the leaf with the basic data type is called ''MTime.fTime.fMilliSec', the column would be called ''MTime.fTime.fMilliSec'' as well. == Changing Column Names == Sometimes the leaves' names might be quite inconvenient like in the example above. To allow to simplify column names, regular expressions (using boost's regex) can be defined to change the names. Note, that these regular expressions are applied one by one on each leaf's name. A valid expression could be: {{{ --map=MHillas\.f/ }}} which would remove all occurrences of '''MHillas.f'''. {{{ --map MHillas\.f/MHillas_ }}} would replace all occurrences of '''MHillas.f''' by '''MHillas_'''. The corresponding call in C++ is `boost::regex_replace(leafname, search, replace)` for `--map search/replace`. As the `--map` option can be given more than once, many and complex replacement rules can be defined. They are applied in sequence, one by one and to all leaves. A single match does not stop the sequence. == Skipping Columns == Sometimes it might also be convenient to skip a leaf. This can be done with the `--ignore regex` option. If the given regular expression yields a match, the leaf will be ignored. Note that the regular expression works on the raw-name of the leaf not the readily mapped SQL column names. {{{ --ignore=ThetaSq\..* }}} will skip all leaves which name contains with 'ThetaSq.'. This option can be given more than once. The corresponding C++ call is `boost::regex_match(leafname, regex)` for `--ignore regex`. === Column Data Types === The data type of each column is kept as close as possible to the leaves' basic data types. If for some reason this is not wanted, the data type of the SQL column can be overwritten with `--sql-type column/type`. This works like the following: {{{ --sql-type=FileId/UNSIGNED INT }}} In this example, ''FileId'' is the name of the SQL column for which the data type ''UNSIGNED INT'' should be used. The second column (UNSIGNED INT) is a basic SQL data type. The option can be given more than once. == Table Creation == It is not very handy if the SQL table has to be created manually beforehand. Therefore, `root2sql` can automatically create the table. To do this, specify `--create`. The query which would be used to create the table can be printed with `--print-create` even when `--create` has not been specified. Tables are created only if the do not yet exist (`CREATE TABLE IF NOT EXISTS`). To ensure recreation of a table, the old table can be dropped with `--drop`. As any insert operation would fail if the required table is dropped and no new one is created, `--drop` always implies `--create`. All columns of the table are created as `NOT NULL` as default. === Database Engine === The default database engine is to create the table with the default of the database. If a database engine (`ENGINE=`) should be forced for the table the `--engine ENGINE` option can be used. Similarly, the row-format (`ROW_FORMAT=`) can be defined using `--row-format FORMAT`. For example: {{{ --engine InnoDB --row-format=COMPRESSED }}} === Primary Keys === For convenience, a primary key can be defined by the the columns which belong to the primary key. To choose the columns which should become primary keys, use `--primary`, for example: {{{ --primary=column1 --primary=column2 }}} Note that the combination of these columns must be unique. == Ignore duplicate entries == Usually, the `INSERT` query would fail if another row with the same primary key exists already. This can be avoided adding the `IGNORE` keyword to the `INSERT` query by `--ignore-errors`, which essentially ignores all errors and turns them into warnings which are printed after the query succeeded. == Update duplicate entries == Another option is to update duplicate entries. This can be done using the `ON DUPLICATE KEY UPDATE` directive. Giving `-duplicate`, you can specify what should be updated in case of a duplicate key. To keep the row untouched, you can just update the primary key with the identical primary key, e.g. {{{ --duplicate='MyPrimary=VALUES(MyPrimary)' }}}. The `--duplicate` resource can be specified more than once to add more expressions to the assignment_list. For more details, see the MySQL manual. == Debugging == For debugging purpose, or to just create or drop a table, the final insert query can be skipped using `--no-insert`. All operation which would alter anything in the database are skipped using `--dry-run` (note that this might create consequent errors). Additional information about the connection are printed using `--print-connection`. Note that this implies additional queries and more traffic and is therefore slightly slower. Using a higher verbosity level (-v), an overview of the written columns or all processed leaves is printed depending on the verbosity level. The output looks like the following {{{ Leaf name [root data type] (SQL name) }}} for example {{{ MTime.fTime.fMilliSec [Long64_t] (MilliSec) }}} which means that the leaf MTime.fTime.fMilliSec is detected to be a Long64_t which is filled into a column called MilliSec. Leaves with non basic data types are ignored automatically and are marked as (-n/a-). User ignored columns are marked as (-ignored-). The complete `INSERT` query can be printed with `--print-insert`. Note that this can be a quite long output. For test purposes, the number of events and the events which are processed can be altered with `--first` and `--max`. == Performance == Note that for performance reason, all data is collected in memory and a single INSERT query is issued at the end. == In case of failure == If a query failed, the query is printed to stderr together with the error message. For the main INSERT query, this is only true if the verbosity level is at least 2 or the query has less than 80*25 bytes. == Returns == In case of success, 0 is returned, a value>0 otherwise. == fits2sql == The `fits2sql` executable works mainly identical to the `root2sql` executable, except that the ROOT-tree here is a so-called FITS-extension (table). Therefore, the `--tree` option is called `--extension`. For debugging, `--print-extension` shows the columns of a FITS extension and `--print-columns` a list of all columns. As a default, integer columns in FITS-files contain signed values. To convert them to unsigned columns, the `--unsigned` option can be given follows by a column name. It can be given more than once to apply that to more than one column. A specialty of FITS-extensions is that they can contains fixed-size arrays of numbers. If the array is called ARR and has 3 fields, the SQL columns will be called ARR[0], ARR[1] and ARR[2]. All modifier options working on columns always alter all corresponding columns at once.