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知って欲しいSQLなこと
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soudai sone
PRO
July 31, 2016
Technology
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1.7k
知って欲しいSQLなこと
中国地方DB勉強会 in 岡山のLT資料です
soudai sone
PRO
July 31, 2016
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Transcript
ͬͯͯཉ͍͠SQLͳ͜ͱ தࠃํ%#ษڧձ
What is it? DB͋Δɺಥવ͘ͳΔ
What is it? ͦΜͳʹཱ͔ͪ͏ ͨͪͷޠͰ͋Δ… ※ϑΟΫγϣϯͰ͢
͋͐͡Μͩ ̍ɹࣗݾհ ̎ɹϧʔϓͰINSERT ̏ɹN+1 ̐ɹςʔϒϧεΩϟϯΛԥΔ ̑ɹ·ͱΊ
͋͐͡Μͩ ̍ɹࣗݾհ ̎ɹϧʔϓͰINSERT ̏ɹN+1 ̐ɹςʔϒϧεΩϟϯΛԥΔ ̑ɹ·ͱΊ
ࣗݾհ ໊લɿીࠜɹେʢͦͶɹ͚ͨͱʣ ྸɿ31ࡀʢࡾਓͷࢠڙ͕͍·͢ʣ ৬ۀɿגࣜձࣾɹΦϛΧϨʢCTOʣ ॴଐɿຊPostgreSQLϢʔβձ ɹɹɹதࠃࢧ෦ ࢧ෦ ɹɹٕज़తʹLLܥݴޠͱ͔RDB͕͖Ͱ͢
͋͐͡Μͩ ̍ɹࣗݾհ ̎ɹϧʔϓͰINSERT ̏ɹN+1 ̐ɹςʔϒϧεΩϟϯΛԥΔ ̑ɹ·ͱΊ
ϧʔϓͰINSERT ͦʔౖ͍ܹͩͨ͠ɻ
ϧʔϓͰINSERT $array = $this->get_hoge(); $this->db->begin(); for ($index = 0; $index
< count($array); $index++) { $this->db->inset($array["{$index}"]) } $this->db->commit();
ϧʔϓͰINSERT $array = $this->get_hoge(); $this->db->begin(); for ($index = 0; $index
< count($array); $index++) { $this->db->inset($array["{$index}"]) } $this->db->commit(); ϧʔϓͷ͚ͩ*/4&35͕ݺΕΔ
ϧʔϓͰINSERT $array = $this->get_hoge(); $this->db->begin(); for ($index = 0; $index
< count($array); $index++) { $this->db->inset($array["{$index}"]) } $this->db->commit(); ϧʔϓͷ͚ͩ*/4&35͕ݺΕΔ ϧʔϓͷ͚ͩDPVOU ͕ݺΕΔ
ϧʔϓͰINSERT ϧʔΫɺόϧΫΠϯαʔτΛ͑
ϧʔϓͰINSERT INSERT INTO hoge (id,name) values (1,’sone1’), (2,’sone2’), (3,’sone3’), (4,’sone4’),
(5,’sone5’), (6,’sone6’) … # ࠷ۙͷFWͳΒྻ͚ͩ͢Ͱ͍͍ this->db->inset($array);
ϧʔϓͰINSERT ͍Ͱ༰ʹΑͬͯ VQEBUFͳΜͰ͢
ϧʔϓͰINSERT $array = $this->get_hoge(); $this->db->begin(); $count = count($array); for ($index
= 0; $index < $count; $index++) { if (empty($array[“{$index}”][“id”])) { $this->db->inset($array["{$index}"]) } else { $this->db->update($array["{$index}"]) } } $this->db->commit();
ϧʔϓͰINSERT ϧʔΫɺ.FSHFจ 614&35 Λ͑ ͔͠͠03.ΫΤϦϏϧμ େ͑ͳ͍
ϧʔϓͰINSERT ——PostgreSQL INSERT INTO ςʔϒϧ໊ VALUES ('̍', '̎', ...ʣ ON
CONFLICT ON CONSTRAINT ੍໊ DO UPDATE SET ΧϥϜ̍='', ΧϥϜ̎='', ...; ——MySQL INSERT INTO ςʔϒϧ໊ VALUES ('̍', '̎', …ʣ ON DUPLICATE KEY ※ࣗͰࢦఆ͢Δ͜ͱ͕ग़དྷͳ͍ UPDATE ΧϥϜ̍='', ΧϥϜ̎='', ...;
͋͐͡Μͩ ̍ɹࣗݾհ ̎ɹϧʔϓͰINSERT ̏ɹN+1 ̐ɹςʔϒϧεΩϟϯΛԥΔ ̑ɹ·ͱΊ
N+1 /
ϧʔϓͰINSERT $array = $this->get_hoge(); $this->db->begin(); for ($index = 0; $index
< count($array); $index++) { $this->db->inset($array["{$index}"]) } $this->db->commit();
N+1 ϧʔϓͷ͚ͩRVFSZ͛Δ
N+1 $users = $this->db->users->get(); $this->db->begin(); foreach ($users as $user_id =>
$user) { if ($user[“pref”] == ‘Ԭࢁ’) { $user[“pref”] = ‘େձ’ } elseif ($user[“pref”] == ‘ౡ’){ $user[“pref”] = ‘ࢁ’ } $this->db->update($user); } $this->db->commit();
N+1 $users = $this->db->users->get(); $this->db->begin(); foreach ($users as $user_id =>
$user) { if ($user[“pref”] == ‘Ԭࢁ’) { $user[“pref”] = ‘େձ’ } elseif ($user[“pref”] == ‘ౡ’){ $user[“pref”] = ‘ࢁ’ } $this->db->update($user); } $this->db->commit(); ͦͦ8)&3&۟ͰQSFGࢦఆͯ͠ 61%"5&ͳΒճ
N+1 ճͷ61%"5&จʹม͑Δ
N+1 UPDATE users SET pref = CASE pref WHEN ‘Ԭࢁ’
THEN ‘େձ’ WHEN ‘ౡ’ THEN ‘ࢁ’ ELSE pref END WHERE pref IN (‘Ԭࢁ’,’ౡ’)
N+1 $"4&ࣜͳͷͰ ৭Μͳͱ͜ΖͰ͑Δ
N+1 $"4&ࣜͳͷͰ ৭Μͳͱ͜ΖͰ͑Δ 03%&3ɹ#:ͱ͔͑Δ
N+1 Ԡ༻ฤ ͭͷ%#Λൺֱͯ͠61%"5&
N+1 JE OBNF BHF TPOF UBLFUPNP
TPVEBJ VTFS@JE CJSUIEBZ QSFG ౡ ࢁ େձ VTFST VTFS@QSPQFSUJFT
N+1 UPDATE users AS u, (SELECT users.id AS id, CASE
WHEN user_properties.birthday > ‘1996-07-30’ THEN ‘ϋλν’ ELSE age END AS age FROM users INNER JOIN user_properties ON user.id = user_properties.user_id AND user_properties.pref IN (‘ࢁ’,’ͳ͝’,’େձ’)) AS tmp SET u.age = tmp.age WHERE u.id = tmp.id
N+1 JE OBNF BHF TPOF UBLFUPNP ϋλν
TPVEBJ VTFS@JE CJSUIEBZ QSFG ౡ ࢁ େձ
͋͐͡Μͩ ̍ɹࣗݾհ ̎ɹϧʔϓͰINSERT ̏ɹN+1 ̐ɹςʔϒϧεΩϟϯΛԥΔ ̑ɹ·ͱΊ
ςʔϒϧεΩϟϯΛԥΔ ϧʔΫɺۚͷؙΛ͑ʢਅإ
ςʔϒϧεΩϟϯΛԥΔ .Z42-ͳΒ44% 1PTUHSF42-ͳΒϝϞϦΛ ·ͣ૿͢
ςʔϒϧεΩϟϯΛԥΔ 1PTUHSF42-͔Β ςʔϒϧεΩϟϯΛ ύϥϨϧΫΤϦʢฒྻॲཧʣग़དྷΔ
ςʔϒϧεΩϟϯΛԥΔ 1PTUHSF42-͔Β ςʔϒϧεΩϟϯΛ ύϥϨϧΫΤϦʢฒྻॲཧʣग़དྷΔ $16ͷΛ૿ͯ͠ԥΕΔΑ͏ʹͳΔ
ςʔϒϧεΩϟϯΛԥΔ ͦΕͰ͍ͳΒ ύʔςʔγϣϯ͔γϟʔσΟϯά
ςʔϒϧεΩϟϯΛԥΔ ͦΕ͕͍࣌͠ ˞ྫ͑σʔλϋεΣΞ ʢ%)8ʣ
ςʔϒϧεΩϟϯΛԥΔ ͦ͏͍͏࣌༻%#Λങ͓͏ ʢ˓˓˓˓ສ͘Β͍͢Δͭʣ
ςʔϒϧεΩϟϯΛԥΔ ςʔϒϧεΩϟϯ͠ͳ͍ઃܭ͕େࣄ
͋͐͡Μͩ ̍ɹࣗݾհ ̎ɹϧʔϓͰINSERT ̏ɹN+1 ̐ɹςʔϒϧεΩϟϯΛԥΔ ̑ɹ·ͱΊ
·ͱΊ ษڧͯ͘͠ΕɺͨͷΉ
·ͱΊ +16(ϝϯόʔΛืूͯ͠·͢
·ͱΊ ϙδγϣϯਓΛҭͯΔ
·ͱΊ ࣍ظࢧ෦܅ͩʂʂ
͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ɻ