ExExeUtilMisc.cpp

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[TRAFODION-3234] Refactor hive meta calls

Hive similarity check was detecting if there is a change in the hive

directory timestamp only. It has been changed to detect the DDL changes too.

Cleaned up code further and removed all the unwanted code.

  1. … 16 more files in changeset.
TRAFODION-3086 Further enhancements to 'DDL on Hive objects'

-- Hive CTAS enhancements

-- CTAS will do create through Hive and insert...select in Traf

-- a cqd can be set if CTAS need to be passed in completely to Hive

-- CTAS 'no load' option can be used to create a Hive

table LIKE a traf table.

Older 'create hive like traf' is removed.

-- explain for CTAS to show ddl, insert...select, upd...stats stmts

-- Truncate enhancements.

-- traf: purgedata, truncate, truncate table

-- Hive: truncate, truncate table

-- 'if exists' option has been added

-- Hive truncate is through new exeutil operator

-- older operator uses LOB interface to clear data.

Maintained as Legacy operator, will be removed.

-- new operator uses Hive to truncate tables

-- explain for truncate to show trunc query that will be sent

-- removed obsolete parallel label op

-- removed obsolete purgedata (fast delete) op

  1. … 30 more files in changeset.
TRAFODION-3086 Traf support for DDL operations on Hive objects

-- Support for TRAFODION-3086. Details in document attached to jira.

Other changes:

-- support for "if not exists", "if exists" clause for create/drop view

-- Support for: truncate T, truncate table T.

-- same as purgedata

-- showddl <tab>, detail

-- unregister hive schema <sch>

-- will unregister all objects in specified schema

-- Support for "if not registered", "if registered" clauss for

register/unregister command.

  1. … 90 more files in changeset.
[TRAFODION-3009] Streamline error handling in Executor utility commands

ComDiagsArea is now allocated only when there are warnings or errors in

all the utility commands.

This requires all the executor utility commands to use a new version of

ExRaiseSqlError to populate diagnostics area.

  1. … 14 more files in changeset.
[TRAFODION-3009] Streamline error handling in Executor utility commands

Removed the need to allocate ComDiagsArea in advance for load command

by refactoring the ExeCliInterface::executeImmediate and

ExeCliInterface::executeImmediateExec methods.

Changes as per the review comments are also made in this commit

  1. … 16 more files in changeset.
[TRAFODION-3009] Streamline error handling in Executor utility commands

ComDiagsArea is now allocated only when there are warnings or error in

all the utility commands except load. In case of load, the ComDiagsArea

is allocated in advance to report error rows count.

This requires all the executor utility commands to use a new version of

ExRaiseSqlError to populate diagnostics area.

[TRAFODION-3017] Simplify the hive client access in Trafodion

Hive Client functions are now moved to a new file HiveClient_JNI.h and

HiveClient_JNI.cpp. Most of the HiveClient functions are static functions

allowing to use HiveClient in Trafodion with ease.

  1. … 33 more files in changeset.
Merge PR 1417 [TRAFODION-2917] Refactor Trafodion implementation of hdfs scan for text formatted hive tables

  1. … 9 more files in changeset.
[TRAFODION-2917] Refactor Trafodion implementation of hdfs scan for text format hive tables

Part-6 changes

Removed the dependency of libhdfs while assigning ranges for hdfs scan at runtime

and for sample file creation during bulk load

  1. … 12 more files in changeset.
Removed usage of system new and moved allocation of LOB globals to be derived from a heap. Moved xLObHdfsRequest also to be derived from a heap

  1. … 13 more files in changeset.
[TRAFODION-2768] Make Trafodion code base to compile in RH7

  1. … 126 more files in changeset.
[TRAFODION-2754] Changing str_sprintf() to use sprintf()

Fix for debug build failure

[TRAFODION-2754] Get statistics cores sqlci or mxosrvr at str_sprintf()

Switched str_sprinf to use the standard sprintf function to ensure

that the format specification and the passed in parameters are consistent

  1. … 65 more files in changeset.
code cleanup, commit #1

  1. … 128 more files in changeset.
TRAFODION-2498 Add support to run hive stmts from traf interface

Syntax:

process hive statement '<string>';

<string>: hive statement starting with create/drop/alter/truncate.

These are the only stmts currently supported.

Ex:

>>process hive statement 'create database trafsch';

will create hive database 'trafsch'

>>process hive statement 'create table trafsch.t (a int)';

will create hive table 't' in hive schema 'trafsch'.

'process hive statment ..' could be issued from any traf interface

(sqlci/trafci/jdbc...)

  1. … 24 more files in changeset.
[TRAFODION-2342] hdfs access threads init/cleanup changes

The worker threads to read hdfs directly was being started

unnecessarily in many cases. Also, ensured that these worker

threads are cleanly exited when the statement is deallocated.

  1. … 10 more files in changeset.
[TRAFODION-2317] Infrastructure for common subexpressions

This is a first set of changes to allow us to make use of CTEs

(Common Table Expressions) declared in WITH clauses and to create

a temp table for them that is then read multiple times in the query.

This also includes a fix for

[TRAFODION-2280] Need to remove salt columns from uniqueness constraints

Summary of changes:

- Adding a unique statement number in CmpContext

- Moving the execHiveSQL method from the OSIM code to CmpContext

- Adding a list of common subexpressions and their references

to CmpStatement

- Adding the ability to the Hive Truncate operator to drop the

table when the TCB gets deallocated

- Adding the ability to the HDFS scan to compute scan ranges at

runtime. Those are usually determined in the compiler. This is

only supported for simple, non-partitioned, delimited tables.

We need this because we populate the temp table and read from

in in the same statement, without the option of compiling

after we inserted into the temp table.

- Special handling in the MapValueIds node of common subexpressions.

See the comment in MapValueId::preCodeGen().

- Moved the binder code to create a FastExtract node into a new

method FastExtract::makeFastExtractTree(), to be able to call

it from another place.

- MapValueIds no longer looks at the "used by MVQR flag" to determine

the method for VEGRewrite. Instead it checks whether a list of

values has been provided to do this.

- Adding a new method, RelExpr::prepareMeForCSESharing, that is

kind of an "unnormalizer", undoing some of the normalizer

transformations.

- Implementing the steps for common subexpression materializations

described below.

- Adding the ability to suppress the Hive timestamp modification

check when truncating a Hive table

- Adding an optimizer rule to eliminate CommonSubExprRef nodes.

These nodes should not normally survive past the SQO phase, but

if the SQO phase gets interrupted by an exception, that could

happen, since we then fall back to a copy of the tree before

SQO. In the future, we can consider cost-based decision on

what to do with common subexpressions.

- Adding CommonSubExprRef nodes in the parser whenever we expand

a CTE reference.

- Adding cleanup code to the "cleanup obsolete volatile tables"

command that removes obsolete Hive tables used for common

subexpressions.

Other changes contained in this change set:

- Optimization for empty scans, like select * from t where 1=0

This now generates a cardinality constraint with 0 rows, which

can be used later to eliminate parts of a tree.

(file OptLogRelExpr.cpp)

- [TRAFODION-2280] Need to remove salt columns from uniqueness

constraints generated on salted tables.

(file OptLogRelExpr.cpp)

- Got rid of the now meaningless "seamonster" display in EXPLAIN.

(file GenExplain.cpp and misc. expected files)

- Suppress display of "zombies" in the cstat command. Otherwise,

these zombies (marked as <defunct>) prevent Trafodion from

starting, because they are incorrectly considered "orphan"

processes. This could require a reboot when no reboot is necessary.

(file core/sqf/sql/scripts/pstat)

Incomplete list of things left to be done:

- TRAFODION-2316: Hive temp tables are not secure. Use volatile

tables instead.

- TRAFODION-2315: Add heuristics to decide when to use the temp table

approach.

- TRAFODION-2320: Make subquery unnesting work with common subexpressions.

Generated Plans

---------------

The resulting query plan for a query Q with n common

subexpressions CSE1 ... CSEn looks like this:

Root

|

MapValueIds

|

BlockedUnion

/ \

Union Q

/ \

... CTn

/

Union

/ \

CT1 CT2

Each of the CTi variables looks like the following, an

INSERT OVERWRITE TABLE tempi ...

BlockedUnion

/ \

Truncate FastExtract TEMPi

TEMPi |

CSEi

The original query Q has the common subexpressions replaced

with the following:

MapValueIds

|

scan TEMPi

Here is a simple query and its explain:

prepare s from

with cse1 as (select d_date_sk, d_date, d_year, d_dow, d_moy from date_dim)

select x.d_year, y.d_date

from cse1 x join cse1 y on x.d_date_sk = y.d_date_sk

where x.d_moy = 3;

>>explain options 'f' s;

LC RC OP OPERATOR OPT DESCRIPTION CARD

---- ---- ---- -------------------- -------- -------------------- ---------

11 . 12 root 1.46E+005

5 10 11 blocked_union 1.46E+005

7 9 10 merge_join 7.30E+004

8 . 9 sort 1.00E+002

. . 8 hive_scan CSE_TEMP_CSE1_MXID11 1.00E+002

6 . 7 sort 5.00E+001

. . 6 hive_scan CSE_TEMP_CSE1_MXID11 5.00E+001

1 4 5 blocked_union 7.30E+004

2 . 4 hive_insert CSE_TEMP_CSE1_MXID11 7.30E+004

. . 2 hive_scan DATE_DIM 7.30E+004

. . 1 hive_truncate 1.00E+000

--- SQL operation complete.

>>

CQDs to control common subexpressions

-------------------------------------

CSE_FOR_WITH is the master switch.

CQD Value Default Behavior

--------------------- --------- ------- ---------------------------------------

CSE_FOR_WITH OFF Y No change

ON Insert a CommonSubExprRef node in the

tree whenever we reference a CTE

(table defined in a WITH clause)

CSE_USE_TEMP OFF Y Disable creation of temp tables

for common subexpressions

SYSTEM Same as OFF for now

ON Always create a temp table for

common subexpressions where possible

CSE_DEBUG_WARNINGS OFF Y No change

ON Emit diagnostic warnings that show why

we didn't create temp tables for

common subexpressions

CSE_CLEANUP_HIVE_TABLES OFF Y No change

ON Cleanup Hive tables used for CSEs with

the "cleanup obsolete volatile tables"

command

CommonSubExprRef relational operators

-------------------------------------

This is a new RelExpr class that is introduced. It marks the common

subexpressions in a RelExpr tree. This operator remembers the name of

a common subexpression (e.g. the name used in the WITH clause).

Multiple such operators can reference to the same name. Each of

these references has a copy of the tree.

Right now, these operators are created in the parser when we expand a

CTE (Common Table Expression), declared in a WITH clause. If the CTE

is referenced only once, then the CommonSubExprRef operator is removed

in the binder - it also doesn't live up to its name in this case.

The remaining CommonSubExprRef operators keep track of various changes

to their child trees, during the binder and normalizer phases. In

particular, it tracks which predicates are pushed down into the child

tree and which outputs are eliminated.

The CmpStatement object keeps a global list of all the

CommonSubExprRef operators in a statement, so the individual operators

have a way to communicate with their siblings:

- A statement can have zero or more named common subexpressions.

- Each reference to a common subexpression is marked in the RelExpr

tree with a CommonSubExprRef node.

- In the binder and normalizer, common subexpressions are expanded,

meaning that multiple copies of them exist, one copy per

CommonSubExprRef.

- Common subexpressions can reference other common subexpressions,

so they, together with the main query, for a DAG (directed

acyclic graph) of dependencies.

- Note that CTEs declared in a WITH clause but not referenced are

ignored and are not part of the query tree.

In the semantic query optimization phase (SQO), the current code makes

a heuristic decision what to do with common subexpressions - to

evaluate them multiple times (expand) or to create a temporary table

once and read that table multiple times.

If we decide to expand, the action is simple: Remove the

CommonSubExprRef operator from the tree and replace it with its child.

If we decide to create a temp table, things become much more difficult.

We need to do several steps:

- Pick one of the child trees of the CommonSubExprRefs as the one to

materialize.

- Undo any normalization steps that aren't compatible with the other

CommonSubExprRefs. That means pulling out predicates that are not

common among the references and adding back outputs that are

required by other references. If that process fails, we fall back

and expand the expressions.

- Create a temp table tmp.

- Prepare an INSERT OVERWRITE TABLE tmp SELECT * FROM cse tree

that materializes the common subexpression in a table.

- Replace the CommonSubExprRef nodes with scans of the temp table.

- Hook up the insert query tree with the main query, such that it

is executed before the main query starts.

Temporary tables

----------------

At this time, temporary tables are created as Hive tables, with a

fabricated, unique name, including the session id, a unique statement

number within the session, and a unique identifier of the common

subexpression within the statement. The temporary table is created at

compile time. The query plan contains an operator to truncate the

table before populating it. The "temporary" Hive table is dropped when

the executor TCB is deallocated.

Several issues are remaining with this approach:

- If the process exits before executing and deallocating the statement,

the Hive table is not cleaned up.

Solution (TBD): Clean up these tables like we clean up left-over

volatile tables. Both are identified by the session id.

- If the executor runs into memory pressure and deallocates the TCB,

then allocates it again at a later time, the temp table is no longer

there.

Solution (TBD): Use AQR to recompile the query and create a new table.

- Query cache: If we cache a query, multiple queries may end up with

the same temporary table. This works ok as long as these queries are

executed serially, but it fails if both queries are executed at the

same time (e.g. open two cursors and fetch from both, alternating).

Solution (TBD): Add a CQD that disables caching queries with temp tables

for common subexpressions.

In the future we also want to support volatile tables. However, those also

have issues:

- Volatile tables aren't cleaned up until the session ends. If we run

many statements with common subexpressions, that is undesirable. So,

we have a similar cleanup problem as with Hive tables.

- Volatile tables take a relatively long time to create.

- Insert and scan rates on volatile Trafodion tables are slower than

those on Hive tables.

To-do items are marked with "Todo: CSE: " in the code.

  1. … 78 more files in changeset.
similarity check changes, commit #1

  1. … 44 more files in changeset.
Additional changes to JIRA TRAFODION-2060 plus couple other fixes

-- interval computations involving tinyint are fixed.

-- hive data mod mismatch error now prints the compile and runtime

timestamps that caused the mismatch.

-- hive test003 updated to truncate data before insert

  1. … 21 more files in changeset.
Regression fix and fixes for emptyDirectory().

  1. … 3 more files in changeset.
Merge remote branch 'origin/master' into lobglobals_fix

Conflicts:

core/sql/cli/Context.cpp

core/sql/exp/ExpLOBaccess.cpp

  1. … 13 more files in changeset.
Changes to move hdfFs handing to the context globals level and remove all disconnects from hdfs from the various components.

  1. … 27 more files in changeset.
JIRA TRAFODION-2022 Some more changes related to hive truncate

-- support for 'TRUNCATE' command for hive tables

-- support for truncate with PARTITION specification

-- separation of traf purgedata and hive truncate code into

different classes and tdbs

-- some cleanup of obsolete older purgedata code

-- new tests added to regress/hive/TEST005

  1. … 23 more files in changeset.
JIRA TRAFODION-2022 Add support for purgedata of hive tables

In addition to purgedata:

-- showplan correctly shows aqr setting

-- data modification check is skipped during insert if overwrite

option was used

  1. … 10 more files in changeset.
hive data modification detection: commit #4

  1. … 24 more files in changeset.
Part 2 of changes to update license text in Trafodion source

This check-in updates license text in all source files in the

core/sql directory. Remaining directories will be done in

later check-ins.

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Move core into subdir to combine repos

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Move core into subdir to combine repos

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Move core into subdir to combine repos

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