It doesn’t. First, a database is a collection of related data, so I assume you mean DBMS or database language.
Second, pagination is generally a function of the front-end and/or middleware, not the database layer.
But some database languages provide helpful facilities that aide in implementing pagination. For example, many SQL dialects provide LIMIT and OFFSET clauses that can be used to emit up to n rows starting at a given row number. I.e., a “page” of rows. If the query results are sorted via ORDER BY and are generally unchanged between successive invocations, then that can be used to implement pagination.
That may not be the most efficient or effective implementation, though.
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On context of web apps , let’s say there are 100 mn users. One cannot dump all the users in response.
Cache database query results in the middleware layer using Redis or similar and serve out pages of rows from that.
What if you have 30, 000 rows plus, do you fetch all of that from the database and cache in Redis?
I feel the most efficient solution is still offset and limit. It doesn’t make sense to use a database and then end up putting all of your data in Redis especially data that changes a lot. Redis is not for storing all of your data.
If you have large data set, you should use offset and limit, getting only what is needed from the database into main memory (and maybe caching those in Redis) at any point in time is very efficient.
With 30,000 rows in a table, if offset/limit is the only viable or appropriate restriction, then that’s sometimes the way to go.
More often, there’s a much better way of restricting 30,000 rows via some search criteria that significantly reduces the displayed volume of rows — ideally to a single page or a few pages (which are appropriate to cache in Redis.)
It’s unlikely (though it does happen) that users really want to casually browse 30,000 rows, page by page. More often, they want this one record, or these small number of records.
I know for MySQL there is LIMIT offset,size; and for Oracle there is ‘ROW_NUMBER’ or something like that.
But when such ‘paginated’ queries are called back to back, does the database engine actually do the entire ‘select’ all over again and then retrieve a different subset of results each time? Or does it do the overall fetching of results only once, keeps the results in memory or something, and then serves subsets of results from it for subsequent queries based on offset and size?
If it does the full fetch every time, then it seems quite inefficient.
If it does full fetch only once, it must be ‘storing’ the query somewhere somehow, so that the next time that query comes in, it knows that it has already fetched all the data and just needs to extract next page from it. In that case, how will the database engine handle multiple threads? Two threads executing the same query?
something will be quick or slow without taking measurements, and complicate the code in advance to download 12 pages at once and cache them because “it seems to me that it will be faster”.
Answer: First of all, do not make assumptions in advance whether something will be quick or slow without taking measurements, and complicate the code in advance to download 12 pages at once and cache them because “it seems to me that it will be faster”.
YAGNI principle – the programmer should not add functionality until deemed necessary. Do it in the simplest way (ordinary pagination of one page), measure how it works on production, if it is slow, then try a different method, if the speed is satisfactory, leave it as it is.
From my own practice – an application that retrieves data from a table containing about 80,000 records, the main table is joined with 4-5 additional lookup tables, the whole query is paginated, about 25-30 records per page, about 2500-3000 pages in total. Database is Oracle 12c, there are indexes on a few columns, queries are generated by Hibernate. Measurements on production system at the server side show that an average time (median – 50% percentile) of retrieving one page is about 300 ms. 95% percentile is less than 800 ms – this means that 95% of requests for retrieving a single page is less that 800ms, when we add a transfer time from the server to the user and a rendering time of about 0.5-1 seconds, the total time is less than 2 seconds. That’s enough, users are happy.
And some theory – see this answer to know what is purpose of Pagination pattern
I am not expert in database design,hope someone able to answer what i should do. situtation is i need to creat a database for book i am collected, book i read, book i will ready, and group by category and need to tag them. curently creat one main table in main table/base - i list all the books name,add author name, add main category,add book tag individually in column. and filter that main table and save view by book i read, by category i want see. i saw airtable/nocodb/baserow have feature to link table: question is: what is the benefit i will get in future if i creat a separate - author table, - main book category table, - tag table and link them with book list instead of chose from multiple select. submitted by /u/FutureLife777 [link] [comments]
We are facing a requirement we need to bring a data warehouse into our ecosystem. We are currently evaluating Snowflake as our primary choice. The business has an expectation that we should be able to not only run reports and analytical queries on the data warehouse (which of course is its specialty), but that they also want applications to be able to connect into it and read customer's data stored on it. The type of queries the applications are expected to execute are fast, and simple queries that will be done continuously through the day, mostly queries that retrieve the customer's general information. My understanding is that data warehouse and Snowflake included are not really suited for this type of queries I mention above given the "columnar" nature of the way we store the data. As we expect to have customer's data copied into a secondary table to be "flattened" so it can be held in a single row, I was thinking that a workaround to increase performance of the customer's table would be to hold the customer's denormalized data into a single VARIANT field (like a JSON) and a primary key field. This to me sounds like an approach to bypass the columnar nature of data warehouses and simulate a Key/Value store. I would like some opinions around this requirement. My understanding is the data warehouses in general are not suited for this type of workload but I may be wrong. Would it be better to Reverse ETL my customer's data into an actual database/KV store? Would my workaround help my use case? NOTE: There is not expectation to use the data warehouse in a transactional fashion, this is read only. Any suggestion is highly appreciated. submitted by /u/Altaflux [link] [comments]
Hey everyone, I need to learn SAS for job-related reasons. I'll be dealing with a lot of population numbers. But must admit I was bad at math in school. My understanding mostly covers basic statistics, such as interpreting charts and diagrams. Do you think it would be challenging for someone with my background to pick up SAS effectively? I'd appreciate any insights or experiences you might have. Thanks a lot! submitted by /u/Ok-Road5378 [link] [comments]
hi, im a beginner and im building a discord bot and i need help with database design for plugins/subplugins. the structure i have thought of. a plugin may or may not have configs, subplugins or values example of plugin with only values: - auto_message: each value is defines a message to send at X interval example of plugin with only configs: - welcome: config stores the message to send and the channel to send it when a member joins a server example of plugin with subpluggins: moderation ├── lockdown ├── mute_ban ├── appeals configs holds like the settings or general parameters. while values, if applicable, holds one 'instance' of the functionality of plugin. feedback please https://preview.redd.it/t53261ni7uqc1.png?width=5777&format=png&auto=webp&s=d4e3dc73598172cbd52fdaacaf4f160909bed362 submitted by /u/aProgrammerHasNoName [link] [comments]
Hello all! Currently I'm learning database design and doing work on extended entity-relational models, I'm having issues understanding a problem. Any experts here I can message and try to get some advice? submitted by /u/ATGravy [link] [comments]
I have googled little to find an answer for this and things i understood are, how the data stored on the memory/disk - database stores data in b tree, hashes, heap, etc. But how spreadsheets are stored on disk? Easy manipulation of data since database stores data in structure way (atleast the structured DBs) such as each column as specific type (int, string, timestamp etc), where spreadsheet has unique cell mechanism, each cell is unique and can be typed any number or string or formula. I have read some difference through internet and could somebody help me to the conclusion with enough explanation? submitted by /u/_praba [link] [comments]
I’m looking for a database to store chat histories between users and chat bots. I would like to store things like message timestamp, message text, sender & recipient ids, upvote & downvote counts. Message text has no maximum length limit. There will be around 500 users sending about 10 messages a day. Average message size is 3 kB. I will build a system on top of the database to generate reports to capture chat bot response quality. Ex: “Show me query/response pairs from the past 3 months where the response received downvotes.” What kind of database(s) should I use? Should I store everything in a relational db? Everything in a relational db except the message text (which can be of any size) and then store the message text somewhere else? Store everything in some kind of noSQL like Cassandra? I’m lost in how I should be thinking to make this decision. submitted by /u/penguins_world [link] [comments]
I'm looking for a relational database system that I can use to gather data which would initially be for my personal use. A relational database is the most suitable way to organize the type of data I'm compiling. I'd like to be able to export the data to be used in a (probably Django) web-app at some point, but that's not totally necessary. I'd be willing to use some cloud-based service as well if nothing local exists. This is probably a very basic question. I've tried googling but I'm not sure what I'm looking at really. submitted by /u/Hot-Raspberry1735 [link] [comments]
I have a API logs table which contains user_id(fk bigint), endpoint_id(fk bigint), created_at_date(DATE) columns. user_id, endpoint_id & created_at_date columns have separate indexes I wanted to get last 7 days logs count of a particular user. I wrote this query select `created_at_date`, count(id) as count from `request_response_logs` where `user_id` = 2 AND `created_at_date` >= '2024-03-20' group by `created_at_date` order by `created_at_date` asc and select `created_at_date`, count(id) as count from `request_response_logs` where `created_at_date` >= '2024-03-20' group by `created_at_date`, user_id HAVING user_id=2 order by `created_at_date` asc I tried using the EXPLAIN query, but sometimes the database uses the index of created_at_date or the index of user_id (only one). This slows down my query execution time. Should I create a new index on two columns (created_at_date, user_id)? I tried creating a new index on the backup table, and the query execution time improved significantly. What should I do in this case because created_at_date & user_id already have separate indexes? submitted by /u/mayur_5 [link] [comments]
Suggestions Hi, I am in the final year of MCA and I want to make my career in the database(database administrator)or in the database field. Please guide me or tell me what to do next or where to start. submitted by /u/rohit_1824 [link] [comments]
Hello! So I'm new to databases, but I'm the only one who has a deep interest in it, so my boss has given me the opportunity to design a database for my team. We currently use a number of Excel sheets that can only be used by one user at a time. They are also not relational, so analysis can be time-consuming. We collect a lot of data on a daily basis. Imagine maybe 20 people adding 5–15 records each day. Everyone enters dates in different formats, names differently each day. Spelling mistakes etc. All of which makes data analysis and compilation of reports a pain. I have created a database, using my computer as the “server”. I now want to create an easy way for multiple users to enter information at the same time. 10 or more at a time. The database at the moment has less than 10 tables. But I imagine it will grow over time. It will have about 30 users, give or take. The majority of them do not know much SQL. So when I was doing a bit of research I came across CRUD apps, using MS Access as the front end and a few other methods. But I'm unsure what would be the easiest and most secure way. In my mind, I would love something web-based, where people can log in and enter the information on a daily basis. Then the information is inserted into the SQL Database automatically. Is this too ambitious for a beginner? Should I stick to SQL? submitted by /u/BlackAndArtsy [link] [comments]
Hello everyone, I'm venturing into the realm of database systems and programming languages and facing a potentially big challenge. Up until now, my experience has mostly been with HTML and working with content management systems like Drupal and TYPO3. A new opportunity has arisen in my career to step up and get familiar with systems like Adabas and Natural. These technologies are completely new to me, and I'm wondering if it's feasible for someone in my position to dive into them. One of my concerns is that my math skills were not the strongest in school (I struggled with it), and I'm unsure how much this might impact my learning process. I realize this is an opportunity for technical advancement and career progression, but I'm pondering if the challenge might be too great. Could anyone with experience in Adabas and Natural share insights on how feasible this transition is? Approximately how long might it take for me to become proficient enough to work with these systems in a professional setting? Are there specific resources or learning paths you would recommend, especially for someone coming from a less technical background? I greatly appreciate any support, advice, or personal experiences you can share. Is it advisable to take on this challenge, or should I possibly look for alternative ways to expand my technical skills? Thank you in advance! submitted by /u/Ok-Road5378 [link] [comments]
Hi guys, I'm trying to figure out how i can go about giving my users the ability to make direct schema changes to their Database provided by Turso. Im following a multi tenant approach where each tenant has its own database. I provide my tenants the database url and authorisation required to directly push a new schema change to turso, however i want to restrict them from deleting certain tables / deleting specific columns on certain tables. I would obviously have to abstract this access away from them in the future, but i would like to provide a similar dx where by they could perform a cli push command. Anyone have any ideas on how to go about this / could point me into a direction i could research to solve this problem. Thanking everyone in advance! submitted by /u/Acropolis1111 [link] [comments]
Ok, So I have downloaded my Mint user data, and they (like everyone else) sent me the most impossible to understand files. I know they are supposed to be in a database but it's like a huge wall of text and I can't figure out how to open it. An example of a line: [{"visitDate":"2022-07-17","visitStartTimeStamp":"2022-07-17 12:45:09","visitEndTimeStamp":"2022-07-17 12:45:17","firstSignInStartTimeStamp":"2022-07-17 12:45:09","firstSignInEndTimeStamp":"2022-07-17 12:45:17","dailySignInAttempts":1,"createAccountProcessSuccess":false,"accountRecoveryPageLoaded":false,"dailyAccountRecoveryAttempts":0,"accountManagerFullNameUpdated":false,"accountManagerUserIdUpdated":false,"accountManagerEmailUpdated":false,"accountManagerPhoneUpdated":false},{"visitDate":"2022-07-17","visitStartTimeStamp":"2022-07-17 12:19:42","visitEndTimeStamp":"2022-07-17 12:20:11","firstSignInStartTimeStamp":"2022-07-17 12:19:42","firstSignInEndTimeStamp":"2022-07-17 12:20:11","dailySignInAttempts":1,"createAccountProcessSuccess":false,"accountRecoveryPageLoaded":false,"dailyAccountRecoveryAttempts":0,"accountManagerFullNameUpdated":false,"accountManagerUserIdUpdated":false,"accountManagerEmailUpdated":false,"accountManagerPhoneUpdated":false},{"visitDate":"2022-07-14","visitStartTimeStamp":"2022-07- This is a tiny representative of one tiny file. How would I go about organizing it or entering it into an SQL or Browsing in an SQL or Excell submitted by /u/l00ky_here [link] [comments]
I hope I'm in the right sub - if not, pls let me know. I am looking for a simple graph database or application which I could use in a non-programmatic way. Something like Airtable or Baserow, but for graphs. I am working in the GRC (Governance, Risk, Compliance) field and I want to visualize my relationships between compliance requirements, policies, other documents, assets, and risks. (Compliance requirements relate to policies, policies related to other documents and to risks, assets relate to other assets and to risks, ...) Some nodes and edges are known at the point of setting up the db/app, but many more will be made by and by (new assets and risks might be added, new policies created etc.). Up to now I already tried to build something with Neo4j, Memgraph, and ArangoDB, and although all those services are great, they are focused on the DB-side, much larger projects, and lack UI to directly edit things. I really need something much simpler, more focused to individual use, but I can't seem to find a solution. Ideally, I could run it locally as for compliance reasons (ha!) I cannot put all the information in an unapproved cloud offering, but even a SaaS offering would be helpful. Any suggestions? 🙂 submitted by /u/South-Run-3378 [link] [comments]
CPU is too high and cant find the reason or root cause We use GCP and its logs and datadog. Any help? submitted by /u/HealthyPackage3636 [link] [comments]
Howdy folks, hope this is the right sub. I'm looking for a host for a POS DB backend for a single small to medium business. The trick is, I'm going to make them an Android app and I have no strategic interest in maintaining or supporting it. So once it's up and running I want to hand it over to the next person and they can have the support contract. So, the right shop will either already have someone who can handle Android or will be able to hire someone. Many thanks in advance for any help Joe submitted by /u/virgoworx [link] [comments]
I've seen most of the time N or M is used to denote "many" in ERDs. Why we can't use M only. What is the different between M and N ? submitted by /u/alien5516788 [link] [comments]
Due to the lack of a name, I am calling it the Category system. Here is the scenario: we have an Article table, and to create a category system to categorize the articles into different categories, we create a Category table and an Item table (with a 1-M relationship). In the Category table, we will have a user ID as a foreign key, just like in the articles table. We create a category, for example, 'Payment', and insert the article ID into the Item table, which does not have any foreign key; it's just holding the value. We created something like this so that we can have a generic table for categories, as we have to add categories to a lot of other tables as well. But the problem here is that it's becoming very tedious work, and multiple calls are made to create an article and then create its category item. Similarly, in the case of deletion too Is there any better way to do this? Working with the current setup is a pain. article { "id": "2" "title": "Intro to stripe", "content": "some content" "user_id": "1", // fk } category { "id": "2" "title": "payment", "entity_model": "article", // table name "user_id":"1", // fk } item { "id": "1" "category_id": "2", // fk "entity_model": "article", // table name "entity_id" : 3 } submitted by /u/Distinct-Ad1057 [link] [comments]
UML help I need to do basic UML diagram for a project. I need to make UML for a ER department (no functions, basic level. It’s extra course). Do you have some comments or suggestions for me? submitted by /u/Tired-Med-Student [link] [comments]
I'm halfway through my university DB project and I need a tool that will include descriptions on the relationships. Any help identifying the tool used here would be appreciated https://i.redd.it/mhu13xywqnpc1.png submitted by /u/20000miles [link] [comments]
I've been frantically looking for a video talking about how we ended up with a flawed extension such as .csv and what could have been a good replacement for it that makes up for its flaws. I can't seem to find it any longer, maybe had gotten deleted but I would love to take another gander at it, or maybe someone else here remembers the videos and could reiterate it's points. Thanks. submitted by /u/Disastrous-Bus-9834 [link] [comments]
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