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- SQL.How can you compare two nullable values safely, and how does IS DISTINCT FROM differ from <>?
- SQL.How are NULL values ordered by ORDER BY, how do defaults differ between databases, and how can you control their placement?
- SQL.How does NULL propagate through arithmetic expressions, and how can COALESCE and NULLIF help handle missing values and division by zero?
- SQL.How does NULL affect join conditions, and why can filtering the right-hand table in WHERE remove unmatched rows from a LEFT JOIN?
- SQL.How do GROUP BY and DISTINCT treat NULL values, even though NULL = NULL evaluates to UNKNOWN?
- SQL.How do aggregate functions handle NULL, and what is the difference between COUNT(*), COUNT(column), and COUNT(DISTINCT column)?
- SQL.How does NULL affect IN and NOT IN, and why can NOT EXISTS be a safer choice when a subquery returns nullable values?
- SQL.How do WHERE, HAVING, and CHECK constraints treat conditions that evaluate to UNKNOWN?
- SQL.Why do column = NULL and column <> NULL not work as expected, and when should you use IS NULL and IS NOT NULL?
- SQL.What is SQL’s three-valued logic (TRUE, FALSE, UNKNOWN), and how do AND, OR, and NOT behave with UNKNOWN?
- ChromeDevTools.Watch all failed requests
- SQL.What are domain types (or constraints on data types), and how do they help enforce data correctness?
- SQL.How does SQL handle comparisons between different data types (for example, string vs number), and why is this dangerous?
- SQL.What is the difference between DATE, TIME, TIMESTAMP, and TIMESTAMPTZ, and which one should be used for business events?
- SQL.How do numeric types like INTEGER, BIGINT, DECIMAL, and FLOAT differ in terms of precision and use cases?
- SQL.What problems can arise from implicit type casting in SQL, and how can it affect indexes?
- SQL.How does NULL differ from 0, an empty string, or FALSE in SQL?
- SQL.What is the difference between CHAR, VARCHAR, and TEXT, and when would you choose each?
- SQL.What is MVCC ?
- SQL.What is AutoVacuum Postgres ?
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Author Archives: Stanislav_Panteleev
Java.Multithreading.What is the use of the volatile, synchronized, transient, native keyword?
🔁 volatile — Visibility in Concurrency Purpose: Ensures that changes to a variable are always visible to all threads.
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Java.Multithreading.On which object does synchronization occur when calling a static synchronized method?
When you declare a static synchronized method in Java, synchronization happens on the Class object, not on an instance of the class.
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Java.Multithreading.How can I check if a thread holds the monitor of a specific resource?
In Java, there’s no direct API like Thread.holdsMonitor(Object obj) — but there are a few ways to indirectly check or debug whether a thread holds a monitor on a specific object.
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Java.Multithreading.What is a livelock?
A livelock is similar to a deadlock, but with a twist: Threads keep changing their state in response to each other, but make no real progress. They’re not blocked (like in a deadlock), but they’re too polite — constantly reacting … Continue reading
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Java.Multithreading.Deadlock
A deadlock is a situation in multithreaded programming where two or more threads are blocked forever, each waiting for the other to release a lock. It’s like two people trying to pass each other in a narrow hallway: Person A … Continue reading
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Java.Multithreading.How does Thread.join() work?
Thread.join() in Java is a method that allows one thread to wait for the completion of another thread before continuing its execution. It’s a synchronization mechanism that ensures a thread finishes before the calling thread proceeds.
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Java.Multithreading.Why are wait() and notify() methods called only in a synchronized block?
Let’s dive into this with clarity and depth: ❓ Why are wait(), notify(), and notifyAll() allowed only inside a synchronized block or method?
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Java.Multithreading.What is the difference between notify() and notifyAll()?
🔔 notify() vs notifyAll() — Core Idea notify() Wakes up one random thread that’s waiting on the same object’s monitor (lock). It’s not guaranteed which thread will be woken if multiple are waiting. Only one continues; the others remain waiting. … Continue reading
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Java.Multithreading.How do wait() and notify()/notifyAll() methods work?
🔁 wait(), notify(), notifyAll() — Overview These methods are used for thread communication: they allow threads to coordinate and cooperate by pausing and resuming execution based on certain conditions. They are methods of java.lang.Object, not Thread — because every object … Continue reading
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Java.Multithreading.Why might a private mutex be needed?
A private mutex (or private lock object) is often used to gain fine-grained control over synchronization without exposing the locking mechanism to the outside world. Here are the key reasons you might want to use a private mutex instead of … Continue reading
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