[
https://issues.apache.org/jira/browse/IGNITE-6917?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16346774#comment-16346774
]
Alexander Paschenko edited comment on IGNITE-6917 at 2/1/18 8:17 AM:
---------------------------------------------------------------------
[~kirill.shirokov], please let me continue with comments.
8. {{BulkLoadParameters}} - do we really need this class? It just has two
fields. For now I see no point in it. Do you expect many more new fields to
come?
9. {{BulkLoadParser}}:
9.1 Unused private field.
9.2 Too long line in {{processBatch}} declaration.
9.3 It seems plain wrong that arguments of {{processBatch}} are related with
JDBC. JDBC is a connectivity interface, nothing else, and these references are
in deeper "guts". We need to decouple these somehow - one day we might work to
support this feature in ODBC, or somewhere else, and then it'd be inevitable.
I'd just introduce an enum for various command types.
10. {{BulkLoadFormat}}:
10.1 Unused import
10.2 Odd empty lines in the beginning of class, in switch, etc
11. {{BulkLoadParser}} and {{BulkLoadFormat}} seem to be related 1:1 - probably
they should be single class and implementations could be merged accordingly
too. Can you come up with a case where we would really need to separate this
entities? Say, one parser for few formats, or one format yielding more than one
type of parser?
12. {{BulkLoadCsvParser}}:
12.1{{ processBatch}} method looks like it could be actually defined in parent
class, and the logic to be changed in subclasses actually lives in
{{parseBatch}}. This is so because command types like {{CMD_FINISHED_EOF}} are
defined on higher level. Can we rework hierarchy accordingly?
12.2 Unused parameter in ctor ( {{params}} ), do we have tests for params at
all?
12.3 Odd empty lines after class header, method declarations
13. {{BulkLoadEntryConverter}}: do we really expect more than one
implementation of this interface? If no, let's just replace it with
{{IgniteClosureX}} or something like that. We have more than enough interfaces
and abstract classes to represent lambdas. *Before refactoring this, please
look at pt.10.3 as well*
14. {{BulkLoadCsvFormat}}: amount of useful code in this class approaches zero,
and this further assures that parser and its format must be one.
15. {{BulkLoadContext}}: too long comment line.
16. {{BulkLoadCacheWriter}}: do we expect more than one implementation of this
interface?quit If no, just remove this class and let {{BulkLoadContext}} know
about streamer. If yes, make it inherit one of Ignite's provided
classes/interfaces for lambdas. *Before refactoring this, please look at
pt.10.3 as well*
17. {{JdbcRequestHandler}}:
17.1 Unused import
17.2 {{processBulkLoadFileBatch}}: all other methods just catch {{Exception}},
please do the same here.
17.3 {{processBulkLoadFileBatch}}: it looks like doing actual job (data
conversion, feeding to streamer) is just plain wrong. Not only it's logic that
could be reused when we'll implement same feature for other interface like
JDBC, it's also not the area of responsibility of JDBC request handler. This
again shows the need of refactoring of {{BulkLoadContext}}: probably we need to
introduce a concrete class that will *a)* wrap streamer and *b)* do conversion.
It will just accept {{List<Object>}} and do with it whatever it wants. JDBC
must not know about this at all, it must just detect correct context and feed
lists of objects to that new class I've mentioned above.
17.4 {{executeQuery}}: I'd move whole stuff of {{if (fieldsCur instanceof
BulkLoadContextCursor)}} above, before {{if (results.size() == 1)}} - it would
decrease scope depth, make code better readable and decrease overall size of
diff (never hurts).
17.5 {{executeQuery}}: {{filesToSendResult}} - doesn't have anything at all to
do with files.
18. {{JdbcBulkLoadContext}}: unused field {{cmdParsingResult}} (getter has 0
usages), not to mention that field name is very misleading - what does JDBC
have to do with parsing?
19. {{JdbcBulkLoadBatchRequestResult}}: quite weird name, I don't think we
should mix words "request" and "result", we never do so in JDBC. Not to mention
that we never send {{JdbcBulkLoadBatchRequest}} *before* we get
{{JdbcBulkLoadBatchRequestResult}} :) I'd just rename this to
{{JdbcBulkLoadAckResult}} as it's sent as an acknowledgement of {{COPY}}
command and never else.
This is not all, more comments will follow.
was (Author: al.psc):
[~kirill.shirokov], please let me continue with comments.
1. {{BulkLoadParameters}} - do we really need this class? It just has two
fields. For now I see no point in it. Do you expect many more new fields to
come?
2. {{BulkLoadParser}}:
2.1 Unused private field.
2.2 Too long line in {{processBatch}} declaration.
2.3 It seems plain wrong that arguments of {{processBatch}} are related with
JDBC. JDBC is a connectivity interface, nothing else, and these references are
in deeper "guts". We need to decouple these somehow - one day we might work to
support this feature in ODBC, or somewhere else, and then it'd be inevitable.
I'd just introduce an enum for various command types.
3. {{BulkLoadFormat}}:
3.1 Unused import
3.2 Odd empty lines in the beginning of class, in switch, etc
4. {{BulkLoadParser}} and {{BulkLoadFormat}} seem to be related 1:1 - probably
they should be single class and implementations could be merged accordingly
too. Can you come up with a case where we would really need to separate this
entities? Say, one parser for few formats, or one format yielding more than one
type of parser?
5. {{BulkLoadCsvParser}}:
{{5.1 processBatch}} method looks like it could be actually defined in parent
class, and the logic to be changed in subclasses actually lives in
{{parseBatch}}. This is so because command types like {{CMD_FINISHED_EOF}} are
defined on higher level. Can we rework hierarchy accordingly?
5.2 Unused parameter in ctor ( {{params}} ), do we have tests for params at all?
5.3 Odd empty lines after class header, method declarations
6. {{BulkLoadEntryConverter}}: do we really expect more than one implementation
of this interface? If no, let's just replace it with {{IgniteClosureX}} or
something like that. We have more than enough interfaces and abstract classes
to represent lambdas. *Before refactoring this, please look at pt.10.3 as well*
7. {{BulkLoadCsvFormat}}: amount of useful code in this class approaches zero,
and this further assures that parser and its format must be one.
8. {{BulkLoadContext}}: too long comment line.
9. {{BulkLoadCacheWriter}}: do we expect more than one implementation of this
interface?quit If no, just remove this class and let {{BulkLoadContext}} know
about streamer. If yes, make it inherit one of Ignite's provided
classes/interfaces for lambdas. *Before refactoring this, please look at
pt.10.3 as well*
10. {{JdbcRequestHandler}}:
10.1 Unused import
10.2 {{processBulkLoadFileBatch}}: all other methods just catch {{Exception}},
please do the same here.
10.3 {{processBulkLoadFileBatch}}: it looks like doing actual job (data
conversion, feeding to streamer) is just plain wrong. Not only it's logic that
could be reused when we'll implement same feature for other interface like
JDBC, it's also not the area of responsibility of JDBC request handler. This
again shows the need of refactoring of {{BulkLoadContext}}: probably we need to
introduce a concrete class that will *a)* wrap streamer and *b)* do conversion.
It will just accept {{List<Object>}} and do with it whatever it wants. JDBC
must not know about this at all, it must just detect correct context and feed
lists of objects to that new class I've mentioned above.
10.4 {{executeQuery}}: I'd move whole stuff of {{if (fieldsCur instanceof
BulkLoadContextCursor)}} above, before {{if (results.size() == 1)}} - it would
decrease scope depth, make code better readable and decrease overall size of
diff (never hurts).
10.5 {{executeQuery}}: {{filesToSendResult}} - doesn't have anything at all to
do with files.
11. {{JdbcBulkLoadContext}}: unused field {{cmdParsingResult}} (getter has 0
usages), not to mention that field name is very misleading - what does JDBC
have to do with parsing?
12. {{JdbcBulkLoadBatchRequestResult}}: quite weird name, I don't think we
should mix words "request" and "result", we never do so in JDBC. Not to mention
that we never send {{JdbcBulkLoadBatchRequest}} *before* we get
{{JdbcBulkLoadBatchRequestResult}} :) I'd just rename this to
{{JdbcBulkLoadAckResult}} as it's sent as an acknowledgement of {{COPY}}
command and never else.
This is not all, more comments will follow.
> SQL: implement COPY command for efficient data loading
> ------------------------------------------------------
>
> Key: IGNITE-6917
> URL: https://issues.apache.org/jira/browse/IGNITE-6917
> Project: Ignite
> Issue Type: New Feature
> Components: sql
> Reporter: Vladimir Ozerov
> Assignee: Kirill Shirokov
> Priority: Major
> Labels: iep-1
>
> Inspired by Postgres [1]
> Common use case - bulk data load through JDBC/ODBC interface. Currently it is
> only possible to execute single commands one by one. We already can batch
> them to improve performance, but there is still big room for improvement.
> We should think of a completely new command - {{COPY}}. It will accept a file
> (or input stream in general case) on the client side, then transfer data to
> the cluster, and then execute update inside the cluster, e.g. through
> streamer.
> First of all we need to create quick and dirty prototype to assess potential
> performance improvement. It speedup is confirmed, we should build base
> implementation which will accept only files. But at the same time we should
> understand how it will evolve in future: multiple file formats (probably
> including Hadoop formarts, e.g. Parquet), escape characters, input streams,
> etc..
> [1] [https://www.postgresql.org/docs/9.6/static/sql-copy.html]
> h1. Proposed syntax
> Curent implementation:
> {noformat}
> COPY
> FROM "file.name"
> INTO <schema>.<table>
> [(col-name, ...)]
> FORMAT <format-name> -- Only CSV format is supported in the current
> release
> [BATCH_SIZE <batch-size-in-bytes>]
> {noformat}
> We may want to gradually add features to this command in future to have
> something like this:
> {noformat}
> COPY
> FROM "file.name"[CHARSET "<charset-name>"]
> INTO <schema>.<table> [CREATE [IF NOT EXISTS]]
> [(col-name [<data-type>] [NULLABLE] [ESCAPES], ...) [MATCH HEADER]]
> FORMAT (csv|tsv|...)
> -- CSV format options:
> [FIELDSEP='column-separators-regexp']
> [LINESEP='row-separators-regexp']
> [QUOTE='quote-chars']
> [ESCAPE='escape-char']
> [NULL='null-sequence']
> [COMMENT='single-line-comment-start-char']
> [TRIM_LINES]
> [IMPORT_EMPTY_LINES]
> [CHARSET "<charset-name>"]
> [ROWS <first>-<last>]
> --or--
> [SKIP ROWS <num>] [MAX ROWS <num>]
> [COLS <first>-<last>]
> --or--
> [SKIP COLS <num>] [MAX COLS <num>]
> [(MATCH | SKIP) HEADER]
> [(REPLACE|IGNORE|ABORT ON [<max-error-number>])) DUPLICATE KEYS]
> [BATCH SIZE (<num> ROWS | <num>[K|M|G|T|P])]
> [COMPRESS "codec-name" [codec options]]
> [LOCK (TABLE|ROWS)]
> [NOLOGGING]
> [BACKEND (DIRECT | STREAMER)]
> {noformat}
> h1. Implementation decisions and notes
> h2. Parsing
> * We support CSV format described in RFC 4180.
> * Custom row and column separators, quoting characters are currently hardcoded
> * Escape sequences, line comment characters are currently not supported
> * We may want to support fixed-length formats (via format descriptors) in
> future
> * We may want to strip comments from lines (for example, starting with '#')
> * We may want to allow user to either ignore empty lines or treat them as a
> special case of record having all default values
> * We may allow user to enable whitespace trimming from beginning and end of a
> line
> * We may want to allow user to specify error handling strategy: e.g., only
> one quote character is present or escape sequence is invalid.
> h2. File handling
> * File character set to be supported in future
> * Skipped/imported row number (or first/last line or skip header option),
> skipped/imported column number (or first/last column): to be supported in
> future
> * Line start pattern (as in MySQL): no support planned
> * We currently support only client-side import. No server-side file import.
> * We may want to support client-side stdin import in future.
> * We do not handle importing multiple files from single command
> * We don't benefit from any kind of pre-sorting pre-partitioning data on
> client side.
> * We don't include any any metadata, such as line number from client side.
> h3. Transferring data
> * We send file data via batches. In future we will support batch size
> (specified with rows per batch or data block size
> per batch).
> * We may want to implement data compression in future.
> * We connect to single node in JDBC driver (no multi-node connections).
> h3. Cache/tables/column handling
> * We don't create table in the bulk load command
> * We may want to have and option for reading header row, which contains
> column names to match columns
> * In future we may wish to support COLUMNS (col1, _, col2, _, col3) syntax,
> where '_' marker means a skipped column (MySQL uses '@dummy' for this)
> h3. Data types
> * Data types are converted as if they were supplied to INSERT SQL command.
> * We may want type conversion (automatic, custom using sql function, custom
> via Java code, string auto-trimming) in future.
> * We will support optional null sequence ("\N") later
> * We may want to allow user to specify what to do if the same record exists
> (e.g., ignore record, replace it, report error with a max. error counter
> before failing the command)
> * We don't currently support any generated/autoincremented row IDs or any
> custom generators.
> * We don't support any filtering/conditional expressions
> * We don't support any files/recordsets/tables with multiple conversion
> errors generated during import.
> h3. Backend / Transactional / MVCC / other
> * We may want an option to select how do we insert the data into cache: using
> cache.putAll(...), for example, or via data streamer interface (see BACKEND
> option)
> * We don't use transactions
> * We don't create locks on rows or tables.
> * We don't try to minimize any indexing overhead (it's up to the user)
> * We may want to minimize WAL impact in future via NOLOGGING option.
> h3. Miscellanea
> * We don't supply an utility to load data
> * We don't currently supply any java loaders (as in PG and MSSQL) that stream
> data (not neccessary from file)
> * Security-related questions are out of scope of this JIRA
> * We don't have triggers and constraints in Apache Ignite
> h1. Implementations from other vendors
> h2. PostgreSQL
> {noformat}
> COPY table_name [ ( column_name [, ...] ) ]
> FROM { 'filename' | STDIN }
> [ [ WITH ]
> [ BINARY ]
> [ OIDS ]
> [ DELIMITER [ AS ] 'delimiter' ]
> [ NULL [ AS ] 'null string' ]
> [ CSV [ HEADER ]
> [ QUOTE [ AS ] 'quote' ]
> [ ESCAPE [ AS ] 'escape' ]
> [ FORCE NOT NULL column_name [, ...] ] ] ]
> {noformat}
> ([https://www.postgresql.org/docs/9.2/static/sql-copy.html])
> h3. Notes
> * Server-side file import
> * Client-side: only from STDIN
> * Protocol implementation: via special command in the protocol
> * Special bulk data loaders in implemented as part of JDBC driver package:
> org.postgresql.copy.CopyManager
>
> ([https://jdbc.postgresql.org/documentation/publicapi/org/postgresql/copy/CopyManager.html])
> * Custom loaders available (e.g.,
> [https://github.com/bytefish/PgBulkInsert.git])
> h2. MySQL
> {noformat}
> LOAD DATA [LOW_PRIORITY | CONCURRENT] [LOCAL] INFILE 'file_name'
> [REPLACE | IGNORE]
> INTO TABLE tbl_name
> [PARTITION (partition_name [, partition_name] ...)]
> [CHARACTER SET charset_name]
> [{FIELDS | COLUMNS}
> [TERMINATED BY 'string']
> [[OPTIONALLY] ENCLOSED BY 'char']
> [ESCAPED BY 'char']
> ]
> [LINES
> [STARTING BY 'string']
> [TERMINATED BY 'string']
> ]
> [IGNORE number {LINES | ROWS}]
> [(col_name_or_user_var
> [, col_name_or_user_var] ...)]
> [SET col_name={expr | DEFAULT},
> [, col_name={expr | DEFAULT}] ...]
> {noformat}
> ([https://dev.mysql.com/doc/refman/5.7/en/load-data.html])
> h3. Notes
> * Both client- and server-side import
> * Protocol implementation via a hack: if result set returned with column
> count == -1, read file name from server and send it immediately.
> h2. Microsoft SQL Server
> {noformat}
> BULK INSERT
> [ database_name . [ schema_name ] . | schema_name . ] [ table_name |
> view_name ]
> FROM 'data_file'
> [ WITH
> (
> [ [ , ] BATCHSIZE = batch_size ]
> [ [ , ] CHECK_CONSTRAINTS ]
> [ [ , ] CODEPAGE = { 'ACP' | 'OEM' | 'RAW' | 'code_page' } ]
> [ [ , ] DATAFILETYPE =
> { 'char' | 'native'| 'widechar' | 'widenative' } ]
> [ [ , ] DATASOURCE = 'data_source_name' ]
> [ [ , ] ERRORFILE = 'file_name' ]
> [ [ , ] ERRORFILE_DATASOURCE = 'data_source_name' ]
> [ [ , ] FIRSTROW = first_row ]
> [ [ , ] FIRE_TRIGGERS ]
> [ [ , ] FORMATFILE_DATASOURCE = 'data_source_name' ]
> [ [ , ] KEEPIDENTITY ]
> [ [ , ] KEEPNULLS ]
> [ [ , ] KILOBYTES_PER_BATCH = kilobytes_per_batch ]
> [ [ , ] LASTROW = last_row ]
> [ [ , ] MAXERRORS = max_errors ]
> [ [ , ] ORDER ( { column [ ASC | DESC ] } [ ,...n ] ) ]
> [ [ , ] ROWS_PER_BATCH = rows_per_batch ]
> [ [ , ] ROWTERMINATOR = 'row_terminator' ]
> [ [ , ] TABLOCK ]
> -- input file format options
> [ [ , ] FORMAT = 'CSV' ]
> [ [ , ] FIELDQUOTE = 'quote_characters']
> [ [ , ] FORMATFILE = 'format_file_path' ]
> [ [ , ] FIELDTERMINATOR = 'field_terminator' ]
> [ [ , ] ROWTERMINATOR = 'row_terminator' ]
> )]
> {noformat}
> ([https://docs.microsoft.com/en-us/sql/t-sql/statements/bulk-insert-transact-sql])
> h3. Notes
> * Server-side import
> * CLI utility to import from client side
> * Protocol implementation: Special packet types: column definition and row
> * Custom bulk data supplied in JDBC driver package:
> com.microsoft.sqlserver.jdbc.SqlServerBulkCopy.
> h2. Oracle
> There is no bulk load SQL command. Bulk loading external data can be achieved
> via:
> * Oracle External Tables
> ([https://docs.oracle.com/en/database/oracle/oracle-database/12.2/sutil/oracle-external-tables-concepts.html])
> * SQL*Loader
> ([https://docs.oracle.com/database/121/SUTIL/GUID-8D037494-07FA-4226-B507-E1B2ED10C144.htm#SUTIL3311]).
> * There is a separate utility for Oracle TimesTen in-memory database:
> [https://docs.oracle.com/database/121/TTREF/util.htm#TTREF324]
> h2. Vertica DB
> {noformat}
> COPY [ [db-name.]schema-name.]target-table
> ... [ ( { column-as-expression | column }
> ...... [ DELIMITER [ AS ] 'char' ]
> ...... [ ENCLOSED [ BY ] 'char' ]
> ...... [ ENFORCELENGTH ]
> ...... [ ESCAPE [ AS ] 'char' | NO ESCAPE ]
> ...... [ FILLER datatype]
> ...... [ FORMAT 'format' ]
> ...... [ NULL [ AS ] 'string' ]
> ...... [ TRIM 'byte' ]
> ... [, ... ] ) ]
> ... [ COLUMN OPTION ( column
> ...... [ DELIMITER [ AS ] 'char' ]
> ...... [ ENCLOSED [ BY ] 'char' ]
> ...... [ ENFORCELENGTH ]
> ...... [ ESCAPE [ AS ] 'char' | NO ESCAPE ]
> ...... [ FORMAT 'format' ]
> ...... [ NULL [ AS ] 'string' ]
> ...... [ TRIM 'byte' ]
> ... [, ... ] ) ]
> [ FROM {
> ...STDIN
> ...... [ BZIP | GZIP | LZO | UNCOMPRESSED ]
> ...| 'pathToData' [ ON nodename | ON ANY NODE ]
> ...... [ BZIP | GZIP | LZO | UNCOMPRESSED ] [, ...]
> ...| LOCAL {STDIN | 'pathToData'}
> ...... [ BZIP | GZIP | LZO | UNCOMPRESSED ] [, ...]
> ...| VERTICA source_database.[source_schema.]source_table[(source_column
> [,...]) ]
> } ]
> ...[ NATIVE
> .....| NATIVE VARCHAR
> .....| FIXEDWIDTH COLSIZES (integer [,...])
> .....| ORC
> .....| PARQUET
> ...]
> ...[ WITH ]
> ......[ SOURCE source([arg=value [,...] ]) ]
> ......[ FILTER filter([arg=value [,...] ]) ]
> ......[ PARSER parser([arg=value [,...] ]) ]
> ...[ DELIMITER [ AS ] 'char' ]
> ...[ TRAILING NULLCOLS ]
> ...[ NULL [ AS ] 'string' ]
> ...[ ESCAPE [ AS ] 'char' | NO ESCAPE ]
> ...[ ENCLOSED [ BY ] 'char' ]
> ...[ RECORD TERMINATOR 'string' ]
> ...[ SKIP records ]
> ...[ SKIP BYTES integer ]
> ...[ TRIM 'byte' ]
> ...[ REJECTMAX integer ]
> ...[ REJECTED DATA {'path' [ ON nodename ] [, ...] | AS TABLE reject-table} ]
> ...[ EXCEPTIONS 'path' [ ON nodename ] [, ...] ]
> ...[ ENFORCELENGTH ]
> ...[ ERROR TOLERANCE ]
> ...[ ABORT ON ERROR ]
> ...[ [ STORAGE ] load-method ]
> ...[ STREAM NAME 'streamName']
> ...[ NO COMMIT ]
> {noformat}
> ([https://my.vertica.com/docs/7.2.x/HTML/index.htm#Authoring/SQLReferenceManual/Statements/COPY/COPY.htm])
> h2. Various solutions from vendors not mentioned above
> * Apache Hive:
>
> [https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DML#LanguageManualDML-Loadingfilesintotables]
> * Apache HBase:
> [http://dwgeek.com/apache-hbase-bulk-load-csv-examples.html]
> * SAP IQ:
>
> [https://help.sap.com/viewer/a898a5b484f21015a377cd1ccb6ee9b5/16.0.11.12/en-US/a6209de484f21015bcb2d858c21ab35e.html]
> * VoltDB:
> [https://docs.voltdb.com/UsingVoltDB/clicsvloader.php]
> * MemSQL:
> [https://docs.memsql.com/sql-reference/v6.0/load-data/]
> (creating pipelines and connecting them to LOAD DATA statement is also a
> notable feature)
> * Sybase:
>
> [http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.help.sqlanywhere.12.0.1/dbreference/input-statement.html]
> * IBM DB2:
>
> [https://www.ibm.com/support/knowledgecenter/en/SSEPGG_9.5.0/com.ibm.db2.luw.admin.cmd.doc/doc/r0008305.html]
> * IBM Informix:
>
> [https://www.ibm.com/support/knowledgecenter/en/SSGU8G_12.1.0/com.ibm.sqls.doc/ids_sqs_0884.htm]
> * Apache Derby (AKA Java DB, Apache DB):
> [https://db.apache.org/derby/docs/10.7/tools/ttoolsimporting.html]
> * Google Cloud Spanner:
> [https://cloud.google.com/spanner/docs/bulk-loading]
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
