Indexes on foreign keys - Ask TOM

Performance poor after analyzeing table Hi Tom, As my understanding, it will use Cost Based Optimzer after analyzing a table. Uncharted 3 pc crack this post. The essential syntax for a foreign key constraint definition in a CREATE TABLE or ALTER TABLE statement looks like this.

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Unindexed Foreign Keys - Charles Hooper's Oracle Notes

Nba 2k14 my career hack. Unindexed foreign keys oracle 11g. I know one advantage is that it eliminates table-level locks and, I have seen the benefit since I have encountered a similar problem.

Find foreign keys with no index - Burleson Oracle Consulting

When I Created the indexes on the. There are two cases where Oracle will place a full table lock on a. And make sure you enough privileges.


Cracked unindexed foreign keys - Ask TOM

This script list the top 10 columns most used in equality predicates or equijoin predicates and which are not indexed. Symptom Possibilities for a ora-1555 to happen, how to find out which event triggered the ora-1555 Other terms rollback segment, snapshot too old ORA-01555. Why unindexed foreign keys cause deadlocks.

Indexing Foreign Keys (Helden)

Native compilation improves the performance of the query execution. Oracle database automatically detects deadlocks and resolves them by rolling back one statement involved in the deadlock, release one set of the conflicting row locks. If you want to be more precise in your analyze you can limit the.


SQL Exercises: Retrieve data from tables

Otherwise, the database will have to do table scans. SQL Exercises, Practice, Solution - Retrieve data from tables Last update on February 26 2020 08: 07: 49 (UTC/GMT +8 hours). Locking behavior depends on whether foreign key columns are indexed.

Download data Concurrency and Consistency - 11g Release 2 ...

Unindexed foreign keys. Rampant author Jeff Hunter notes that there is a table-level locking issue prior to release 11g: ALTER TABLE emp ADD CONSTRAINT emp_fk1 FOREIGN KEY (deptno) REFERENCES dept (deptno); Once this constraint is enabled, attempting to insert an "EMP" record with an. Eg: we have a table ERROR_TBL for 3, 528, 434 rowsNam.


Performance problem with unindexed foreign keys

Quantum conundrum crack for gta. As you did not provide a version number I can not help you with specifics but I suggest you look up the article and read it. Unnecessary indexes. This guide also describes performance best practices for creating an initial database and includes performance-related reference information.

Oracle - Unindexed Foreign Key leads to TM Enqueue

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THE RAJESH BLOG: Un-Indexed Foreign key

Also, the DBMS_LOCK package enables user-defined locks to be released and allocated at will and even held over transaction boundaries. PK Lookup During FK Insertion. Null rule: A null rule is a rule defined on a single column that allows or disallows inserts or updates of rows containing a null (the absence of a value) in that column.

Oracle Database Administration

Question: How do I find unindexed foreign key columns? There are two cases where Oracle will place a full table lock on a There are two cases where Oracle will place a full table lock on a child table after modification of the parent table. For this reason foreign.


Metadata - List of foreign keys and the tables they

Lock Mechanism in Oracle Oracle Database provides: data concurrency, consistency. Change Management Pack 11g Datasheet. I have installed Oracle database 11g R2 with a customized application.

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How to violate a foreign key in oracle. For that type of information, see Oracle Database Concepts. I was recently reminded of the chaos that can be caused by an unindexed foreign key column when there are corresponding updates or deletes from the parent table.

Serial key tuning - Oracle Information

Oracle Database 11g BI and Data Warehousing D52358. Deadlocks with unindexed foreign keys There are various attributes which can be specified when creating foreign key constraints, without an index on the foreign key column(s), Oracle has no option but to attempt to get a table lock on the child table while it performs it's maintenance. Effective data collection and analysis is essential for identifying and correcting performance problems.


Foreign key indexing tips - Oracle Consulting, Oracle

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Indexing Foreign Keys

March 2, 2020 ashokanb Leave a comment. Some unindexed joins and correlated subqueries may also require use of a temporary segment. Read honest and unbiased product reviews from our users.


Unindexed foreign keys

Enqueue waits are waits for locks. This could be as a result of updating the primary key or deleting a row, but not by inserting. Assassins creed 3 crack files.

Performance poor after analyzeing table - Ask TOM

The glaring exception to this is a code table (short code to long description). We have a nightly Oracle Scheduler job on all of our Oracle Databases that emails us the results from such a query in order to find new instances of those pesky unindexed foreign keys – Kris Johnston Mar 18 '16 at. Oracle Database 2 Day + Performance Tuning Guide is task-oriented.


FTS5 tables, = vs. MATCH, index 0, and "error: no such column"

The SQLite FTS5 Extension page presents this statement about queries on FTS5 tables:
The following three queries are equivalent.
SELECT * FROM email WHERE email MATCH 'fts5';
SELECT * FROM email WHERE email = 'fts5';
SELECT * FROM email('fts5');
This statement is logically correct (well, mostly: see below). However, I have encountered quite serious performance issues with using the = operator on big tables (1,000,000 records or more) with unique values, where such issues do not apply to the MATCH operator.
Performance Issues
To illustrate (and validate my understanding of) the problem, I wrote some code that generates an FTS5 table ("test") with a single column ("content") and fills it with 10,000,000 records, each with a unique integer. It then executes 100 queries to search for one of the records using the MATCH operator and displays the average time. Finally, it performs the same test using the = operator.
import os, random, sqlite3, sys, time filename = 'fts5_test.sqlite' if os.path.isfile(filename): os.unlink(filename) db = sqlite3.connect('fts5_test.sqlite') db.execute('create virtual table test using fts5(content)') size = 10000000; batch_size = 100000; trials = 100 for i in range(0, size, batch_size): values = tuple((i + j,) for j in range(batch_size)) db.executemany(f'insert into test values (?)', values) avg_time = 0 for i in range(trials): start = time.time() db.execute("select 1 from test where content match ?", (random.randint(1, size),)).fetchall() avg_time += time.time() - start print(f'\MATCH: Trial {i + 1} - average time per lookup: {avg_time / (i + 1):<1.4} seconds', end='') print('') avg_time = 0 for i in range(trials): start = time.time() db.execute("select 1 from test where content = ?", (random.randint(1, size),)).fetchall() avg_time += time.time() - start print(f'\r=: Trial {i + 1} - average time per lookup: {avg_time / (i + 1):<1.4} seconds', end='') print('') 
MATCH: Trial 100 - average time per lookup: 6.254e-05 seconds
=: Trial 100 - average time per lookup: 1.599 seconds
The MATCH operator performs literally 25,000 times faster than the = operator. This is not consistent with my understanding of the term "equivalent."
More Detail
This difference is baffling, because if there is any performance difference, I would expect the exact opposite behavior: = is a simple value comparison that can likely be performed in O(1) with a hashcode lookup, while MATCH is a much more sophisticated and feature-rich text comparison.
The extremely long query times for the = operator suggest an O(n) search process - basically, scanning the whole table. But some analysis suggests that SQLite doesn't think it's doing that:
sqlite> explain query plan select * from test where content match -1; QUERY PLAN `--SCAN TABLE test VIRTUAL TABLE INDEX 1: sqlite> explain query plan select * from test where content = -1; QUERY PLAN `--SCAN TABLE test VIRTUAL TABLE INDEX 0: 
Apparently, SQLite says that it's using INDEX 0 for this query, but the performance issues suggest that it's just scanning the entire table. I can't tell whether "INDEX 0" is supposed to indicate an unindexed operation, or that SQLite thinks it's using an index, and is just using it very badly.
Use Case
I have a big data set with records that include both primitive values (date, int, simple strings, etc.) and text that I'd like to be text-searchable. I understand, from the FTS5 documentation, that an FTS5 table requires all columns to be FTS5-indexed. Therefore, for each record, I store the primitive values and a primary key in a "main" table, and I store the FTS5 values in an FTS5 table. I relate the tables by including a column in the FTS5 table that contains the primary key of the "main" table.
Storing the data works fine. However, a problem arises when recomposing the record (or, worse, lots of records) from the FTS5 table, because I need to index into the FTS5 table to find each record by the primary key:
sqlite> select * from fts5_table where primary_key = '12345'; 
As the table fills up, this query takes forever to execute. I first noticed the problem after creating some really big tables (400 gigabytes of text in the FTS5 table) and then trying to retrieve them - an operation that should have taken a few minutes was still running after 8 hours, and just reading, endlessly, from disk.
My solution was to replace the = operator with MATCH, and the problems resolved.
I will acknowledge that my use case is perhaps a bit off-label: that using an FTS5 index for 10,000,000 records to store a column with 10,000,000 small, primitive values is atypical. However, the objective of wanting to relate records in an FTS5 table to another table through a foreign-key relation is pretty standard. Also, this could be avoided by creating the FTS5 table with a non-FTS5 column that can be normally indexed and normally queried - but the limitation that FTS5 tables can ONLY have FTS5-indexed columns cannot be circumvented.
Additional Problems with MATCH and Negative Numbers ("error: no such column")
Actually, the general statement about = and MATCH being logically equivalent is also incorrect. I encountered new issues with tables for which the primary key is a negative number, such as a 64-bit signed hashcode. For instance:
sqlite> select * from test where content = 1; # OK sqlite> select * from test where content = -1; # OK sqlite> select * from test where content match 1; # OK sqlite> select * from test where content match -1; # error: no such column: 1 
The error message threw me for a loop, since the query isn't asking for "column 1," but for value -1 in column "content." As it happens, FTS5 has this goofy behavior of interpreting dashes in the fields of a MATCH query as a column filter.
The apparent solution is to enclose the values in TWO quoted characters:
sqlite> select * from test where content match '-1'; # error: no such column: 1 sqlite> select * from test where content match "-1"; # error: no such column: 1 sqlite> select * from test where content match '"-1"'; # OK 
Note that the order matters - it must be double quotes INSIDE single quotes - and that the opposite order fails:
sqlite> select * from test where content match "'-1'"; # error: syntax error near "'" 
This is an extremely janky solution, but it does work. Hope this is helpful to anybody who encounters the peculiar "error: no such column" message. (Also, the error message should be changed, since it is quite misleading and even surprising.)
Addendum #1: Tokenization
While the above syntax will result in successful queries, the table won't work quite as expected:
sqlite> insert into content values (1); # OK sqlite> select * from test where content match '"1"'; 1 sqlite> insert into content values (-1); # OK sqlite> select * from test where content match '"-1"'; -1 1 
Why did it select both? The janky double-quotes syntax should force it to treat the dash as a literal symbol, but it's not doing that: it is not treating it like a metacharacter, but otherwise ignoring it.
The solution is to affirmatively declare that a dash symbol is among the tokenized characters while creating the table:
sqlite> create virtual table test using fts5(content, tokenize = "unicode61 tokenchars '-'") 
If the table is created this way, the table works as expected, and the above syntax returns only -1.
Addendum #2: Programming Syntax
The janky quote syntax creates a small problem in Python (and likely every other language), since SQL queries for SQLite are specified as strings... which also require a quote. So this fails:
db.execute('select * from table where content match ?', (-1,)) # syntax error 
db.execute('select * from table where content match ?', ('-1',)) # syntax error 
But this works:
db.execute('select * from table where content match ?', ('"-1"',)) # OK 
...because apparently, Python interprets '"-1"' as the string "-1" and encloses it in single-quotes. This can also be parameterized:
n = -1 db.execute('select * from table where content match ?', (f'"{n}"',)) # OK 
The syntax makes me break out in hives, but it works, and that's what counts, I guess.
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[OC] Curators Hiatus 2: Earth Geopolitics circa 2160CE

First Episode -- End of Book 1 -- Previous -- Book 2

Earth (Political)

From Galactipedia, the Free Encyclopedia of the Milky Way
Earth [CI:1742660] is the Human homeworld. This page covers the current era (as of 2160CE) political situation on Earth and its interstellar Human colonies. For information about Earth's physical characteristics, Human anatomy, lack of Curation, economics, or advanced electronics and fold technology, see the linked articles.
Unlike most Curated worlds Earth does not have a unified planetary government. Earth's governance and its history is quite complex, having coalesced from a chaotic legacy of conflict and shifting alliance. At the time Humans achieved space travel via massively complex and dangerous chemical rockets around 1950CE, there were nearly two hundred independent governing bodies called "countries" asserting control over various geographical areas of the Earth. Today there are four governing bodies which together assert control over nearly the entire planetary land mass.

The Four Modern Powers

Main Article
The four governing bodies of Earth today are:
  1. The Russo-American Concordance controls the former country of Russia and its satellites and the continents of Europe and North and South America.
  2. China controls roughly the southeastern quarter of the Asian continent. Its coastline runs continuously from north of the Korean peninsula to areas of the former country of Bangladesh. Modern China includes the repatriated rogue state of Taiwan, the Korean peninsula, and all of the other formerly separate countries of mainland southeast Asia. Inland its territory ranges west to the Himalayas and north to the Russian border. The Chinese protectorate also includes Madagascar and much of southern Africa through "administrative councils" which are actually arms of the Chinese government.
  3. The Indo-Japanese Co-Prosperity Sphere controls the former country of India, the entire Middle East, northern Africa, and through what began as a strategic alliance the Pacific island territories of Japan, the Philippines, Indonesia, Singapore, and most of the scattered Pacific islands of Polynesia which are still above sea level.
  4. The continent of Australia remains an independent geopolitical entity with its own government. Modern Australia also governs the island subcontinents of Papua New Guinea and New Zealand.

Russo-American Concordance

Main Article
The countries of Russia (heading the "Soviet Union") and America (the "United States of America," or USA) were two of Earth's great superpowers and bitter enemies throughout the mid twentieth century. Around 1990CE the Russian government collapsed, and after a brief dalliance with democracy Russia was effectively taken over by representatives of organized crime, which had become the most powerful players in the chaotic post-collapse economic environment.
After 1990CE relations between Russia and America warmed as powerful business interests began to merge. Around 2020CE the Russian government began to openly subvert the democratic processes of states it was interested in controlling, including America, by the use of online propaganda, orchestrated blackmail of key politicians, and "hacking" of the primitive electoral processes in use then. By 2050CE Russia had effectively but at that point clandestinely assumed control of the governments of at least twenty other countries by these methods.
By 2070CE the growing Concordance had a stranglehold on commerce in much of the northern hemisphere and the Americas which it used ruthlessly to expand its influence and consolidate its control. Although it was not officially a single entity at this point the member countries were bound by various treaties and agreements which assured that they would usually act in concert. The true ruling government consisted of Russian oligarchs and organized crime family figureheads who moved their base of operations from Moscow to Atlanta as climate change made the weather more unpredictable in Europe and Asia.
It was the Russo-American Concordance, through its vassal member the United States of America, which launched the Hermes, the interplanetary fold drive test mission which attracted the Sevillians to make First Contact and introduced Humans to the Curated galactic community.
By 2090CE the Concordance had effective control over all of its modern extent. Amid the chaos of rising sea levels, shifting climatic regions, and population displacements including the interstellar diaspora to the human colonies, the Concordance abruptly dropped the fiction that it was an alliance of nominally independent nations. Overnight it erased all previously existing political boundaries within its domain and replaced them with a simplified map of administrative districts mostly bounded by lines of latitude and longitude, and made roughly equal in scope according to a formula based on population, economic production, and land area. Reference to the previous national identities or boundaries in print, broadcast, or online was prohibited by law and by 2120CE nearly all mention of the various countries that had coalesced to form the Concordance had been eliminated from popular media.


Main Article
China is by most assessments the oldest political entity on Earth, tracing its origin to the legendary Xia dynasty of roughly 2000BCE. In that time it has not been a single entity, having repeatedly fractured and re-unified, but it has retained a recognizable and continuous geopolitical identity for at least 4,000 Earth years. While this may seem like a short time in galactic terms, it is an extremely long run for a Human institution.
As Russia subverted the governments of the future Concordance in the mid 21st century, China recognized an opportunity to consolidate its own sphere of influence and began by assimilating the rogue state of Taiwan. It followed by using subversion techniques to assimilate the Korean peninsula and over time the other separate mainland nations of southeast Asia.
Rather than expand toward India, Russia, or Japan, where the Chinese knew they would meet formidable resistance, China consolidated its hold on the now deforested island of Madagascar and used it as a beachhead into southern Africa. The government of the country of South Africa was making a bid of its own to be a regional power in the 2060's, but China was able to overrun them with military and political resources for which the Africans had no answer. China did not adopt its new holdings in Africa into its official national territory as the other superpowers would do with all of their conquests, but its control over those territories is undisputed and China relies heavily on the natural resources of its African colony districts.

Indo-Japanese Co-Prosperity Sphere

Main Article
As of 2010CE the country of India was widely lauded as being the Earth's largest democratic government. Viewing the Russo-American expansion and consolidation and the new Chinese aggression with alarm in the 2050's the Indian government reached out to Japan to create an alliance.
Japan was one of the most technically competent countries on Earth at the time but very poor in natural resources. At first the alliance was friendly and widely considered to be mutually beneficial. But the Japanese government was being subverted by the Yakuza organized crime clans much as Russia's had been by its organized crime gangs in the early 21st century, and eventually the crime family rulers of Japan used the same tools the Russians had used to subvert and control India's democratic government. Throughout the second half of the 21st century the alliance expanded aggressively across the Middle East and into northern Africa, taking advantage of the chaos caused by climate change. It also assimilated most of what remained of Polynesia with little resistance. Eight years after the Russo-American Concordance erased all the old national boundaries within its domain, at the opening of the 22nd century the Indo-Japanese alliance followed suit.


Main Article
Australia is the only geopolitical entity of the modern era which is largely unchanged from its extent and polity of the 19th century. Being a self-contained geographically isolated large island nation Australia had nowhere to easily expand to, and no reason to fracture. Its remoteness and relative lack of natural resources made it an unattractive target for conquest by the larger superpowers. While the other powers had to aggressively reduce their populations via the fold diaspora, Australia was actually able to increase its population in the 22nd century because new weather patterns made some formerly desert areas of the continent arable. The formerly separate island nations of Papua New Guinea and New Zealand joined Australia voluntarily rather than be assimilated by Indo-Japan.
Seeing what happened in India and America, the Australians introduced measures to "inoculate" their electoral processes from foreign tampering. As of 2160CE they are the only large political entity on Earth to still practice democracy in a meaningful form.

International Relations

The Russo-American Concordance, China, and Indo-Japanese Co-Prosperity Sphere all maintain their own independent and self-sufficient semiconductor manufacturing lines, from the harvest of natural raw materials to the final production of products such as fold and supergravity drives. The Australians manufacture parts and provide services for the other producers, but do not produce final products of their own for the galactic market.
Although they are nominally independent the three powers which provide advanced Earth products cooperate as to pricing and delivery, often shipping product for one another. Although humans are famously warlike there has not been an actual war between major powers on Earth since 2048CE, making the modern reign of the four powers one of the most peaceful eras in modern Human history. The extents of the four powers have been stable and mostly uncontested since 2130CE.

The Human Fold Diaspora

Main Article
The Earth's climate has warmed dramatically in the last three centuries due to atmospheric pollution from Humans' early industrial efforts. By the late 21st century this had caused the planet's ice caps to collapse, raising the sea level by over ten meters and dramatically altering historic patterns of storm formation and precipitation. The rising sea has inundated much of the formerly arable land and many low-lying population centers, and changes in weather patterns have disrupted the productivity of other previously arable lands. By 2080CE famine, storm casualties, and epidemics were causing the total Human population to decrease for the first time in recorded history.
Having invented fold ships which could land on an unimproved planet without ground support, Humans began scouting for suitable Curated but unindexed colony worlds in the 2060's. After the hybrid Hyacinth-Human giant landing fold ship Laputa began flying the Humans began an aggressive campaign of emigration and colonial development. The Laputa was so successful the Humans almost immediately began contracting with other races to build more Laputa class ships, and throughout the next thirty years acquired roughly one per year. The reduction of Earth's population from its height of 15 billion to the 2150CE level of 800 million was partly accomplished by the emigration of roughly seven billion to the colonies.

Human Colonial Governance

Main Article
The four powers of Earth mutually agreed that attempting to maintain an interstellar imperial presence would be a foolish and impractical waste of resources. All of the human colonies have their own local global governments on a more typical galactic model, with democratically elected representative councils. Also unlike Earth, where the technology is banned, the colonies make use of Curator derived nanite tech, which makes possible a post-scarcity economy in which no individual has to find a source of monetary income in order to survive.
Some effort was made in founding the colonies to make sure none of them would be dominated by any single popular Human culture, so all of the colonies feature a mix of racial, religious, and political heritage similar to that which remains on Earth.

See Also

Economy of Earth Hyacinth Coalition Trading with the Humans: A History by King Henry of Hyacinth List of Human Colony Worlds Non-Curator Sourced Fold Technology
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